Shop Safety for CNC Machinists

Shop safety includes the use of personal protective equipment (PPE) as well as lockout tagout policies.

Shop Safety? Go ahead. Roll your eyes. Get it out of the way now. We have all seen the cheesy safety movies with terrible acting and fake blood. Don’t worry though, this isn’t like that – I’m a terrific actor. Seriously though, I took classes.

All joking aside, I know how easy it is to laugh it off and ignore the safety rules. Let’s be honest, a lot of those safety rules make all of our lives in the shop more difficult. I had one safety officer (any of you working for a large corporation will know exactly the type I am talking about) who required us to make Plexiglas covers for every moving part on all of our machines. Try setting a gear hobbing machine through three levels of six year old plexi. You get the point. However, one thing I learned very fast was that those safety rules were not created to make you less productive. They were created and enforced to – get this – KEEP US SAFE! One close call is usually all it takes (that’s all it took me) to start taking those rules a little more seriously and my goal today is to prevent the close call and maybe just speak some sense into you. If I manage to save a finger or two, or even a pint of blood, then I have achieved my goal!

Shop Safety PPE or personal protective equipment can include a wide range of items, but should always start with proper eye and ear protection.
Shop Safety PPE – Personal Protective Equipment starts with eye and ear protection.

Why don’t we start with my favorite basic rule – If you don’t do it while you’re driving, don’t do it while you’re machining. Don’t sleep, eat, consume alcoholic beverages, use drugs, call Grandma, text your buddies, or make unsafe lane changes while running your machine. Whether it is a high end CNC or an engine lathe it requires your full and undivided attention at all times. All of these machines are incredibly powerful tools that don’t have brains – don’t argue, even your half million dollar five-axis VMC doesn’t think for you. Machines do what you tell them to do, make sure you are aware of what you’re telling them. Common sense is not a part of the final sale, you have to bring that with you. Respect the equipment, it deserves it.

Personal Protective Equipment (PPE) for Shop Safety

Personal Protective Equipment (PPE) is a very important aspect of shop safety. This includes everything from safety glasses to gloves, earplugs and aprons. I have worked in shops that required hard hats because of a 20 ton overhead crane, as well as shops that would send you home if your sleeves were loose or long, or long hair wasn’t pulled back. On the opposite end of that spectrum I have worked in shops where sneakers and flip flops were more common than steel toe boots and safety glasses. Just because your company may not enforce the rules does not mean you shouldn’t follow them. If you ever need the safety glasses you will be glad you have them on. Always be your own advocate when it comes to safety, because even if you have that annoying safety guy always sneaking around to write you up for not putting your earplugs in he can’t be there all the time, and all it takes is a split second for things to go wrong.

Shop Safety Gloves can protect your hands when moving sharp material but could harm them if caught in moving parts of a CNC machine so know when to wear them and when not to.
Shop Safety Gloves – know when to wear them and when not to.

Shop Safety – Gloves … when to wear them and when NOT to!

Gloves are a tricky piece of PPE, because depending on what you are doing and which machine you are running they can be either helpful or harmful. Very harmful. If you are going over to the stock rack to grab a plate of steel a thick pair of leather work gloves will protect you from any sharp edges while you carry that stock. However if you are running ANY machine with a running spindle DO NOT wear gloves. Whether it is a CNC machine, a lathe, a knee mill, or a drill press wearing gloves near a rotating spindle and spell disaster. A lot of folks think they can get a better grip on their part while running the drill press if they were a heavy pair of gloves and the sharp edges won’t cut them. I can tell you first-hand how disastrous this can be – it is very easy for the drill or material to grab right onto that drill, and I will let your imagination take you from there. Assuming safety features haven’t been disabled (again, the common sense thing) then most CNC machines will not allow you to put your hand near the spindle while it is running. However, on the off chance you have both the chance and opportunity – DON’T! The only times that I ever suggest wearing gloves when running a CNC are either when fingerprints need to be avoided or when the coolant tank is full of month old flood coolant and your company hasn’t invested in anti-microbial/anti-bacterial additives. I have seen some pretty nasty skin infections from old coolant, so make sure you keep that in mind. In these cases wear latex nitrile gloves – tight fitting non leather gloves that will break with minimal force if necessary.

Avoid “Danglers” for Shop Safety

When running manual machines especially it is very important to keep any “danglers” in mind. Long sleeves, pony tails, baggy shirts, jewelry, etc. Anything that hangs off of your body – keep it to a minimum. Again, all of the above could spell disaster. I know you want to be the best dressed guy in the shop, but I would rather be the guy with all his limbs and digits. Just my personal preference.

Shop Safety Lockout Tagout is extremely important in the machine shop and when working around CNC milling machines.
Shop Safety Lockout Tagout is often overlooked but is critical when working around CNC machining centers.

Lockout/Tagout – take it seriously!

Finally I want to discuss Lockout/Tagout. The number of people whom I witness not following this procedure enough (myself included at times) is alarming. Lockout/Tagout for anybody who is not familiar is the process of powering down the machine and locking the power switch with a lock that only the service technician has the key for. The purpose here is to prevent anybody but the service tech from doing ANYTHING with the machine. Every time you service that machine without powering down and locking it out you are inviting accidents. Especially when dealing with CNC machines the consequences of this mistake could be fatal- it’s not worth the extra thirty seconds.

Safety is absolutely no joke. PPE can be uncomfortable, inconvenient and cumbersome. Safety procedures can be time consuming. Plain and simple, you never want to be in a position where you finally understand why they enact all these rules – just trust in them and follow your common sense. It is the most useful tool you will have with you in the machine shop. Stay safe friends.

Micro drilling: An incredible (and Incredibly Frustrating) Adventure

Micro drilling using drills far smaller than a human hair requires experience, research and the right milling machine.

So micro drilling has never been my forte.  I have done a lot of drilling but never anything much smaller than 1/64th or so.  Well friends, if you were a part of that club too then there is a whole other world of drilling that you have never experienced, and there are some pretty amazing things going on.  Some of the more recent research I have done on micro drilling has been very eye opening, and the project I am currently working on has been one of the most challenging in my career – all to drill holes slightly larger than a human hair.  We will discuss many of the things to watch out for and some basic parameters to start some of your own research projects.

Much like anything else in the machining world, the numbers don’t lie.  Many of the same formulae apply.  However, there is MUCH less room for error.  Everything from the length of your flute to the geometry on the tip of your drill needs to be scrutinized, and with micro drilling there is no easy answer for anything.  Tooling manufacturers will be your best resource for parameters to start with, since they are the experts on their own tools.  I am not a tool salesman, so I am not going to promote one brand over the other.  That, friends, needs to be part of your research.

Step 1 in Micro Drilling – Research the Material

Micro drilling stainless is shown in these impressive Xrays of a 0.004" hole drilled 0.040" deep in stainless steel rods.
Micro drilling stainless: Xrays of a 0.004″ hole drilled 0.040″ deep in stainless rods.

That brings me to step one of your micro drilling adventure.  Research.  You need to know your machine, you need to know your material, you need to know your coolant and coolant system, and you need to know your tools.  When I say you need to “know” I don’t mean a basic knowledge.  Research it, become as much of an expert as you can on everything you are doing before you even consider cutting metal.  When it comes to micro drilling in general there is a lot of research out there, and much of it provides conflicting or confusing information.  Arm yourself with the knowledge to fight through it and you will be OK. Research different coolants, research different drills.  Drill suppliers and coolant suppliers should both have people that you can talk to over the phone for more information – most importantly specific information about your material.

Micro drilling plastic like these tiny holes drilled in small cavities on a Delrin part.
Micro drilling plastic – this shows small holes drilled through circular cups (or cavities) in a Delrin part.

Currently I am drilling .008” holes into 15-5 PH stainless.  The first thing I did was learn as much as possible about 15-5 stainless.  It’s an interesting material because it is considered a stainless steel, but it acts like a die steel.  Because I knew that before doing my research I was able to navigate my way through the tooling manufacturers’ charts, skip right by stainless steel and take the parameters from the die steel section.  I avoided many headaches, because the parameters were very different – much slower spindle speed for the stainless.  My point is, material knowledge is key.  Know that first.

Step 2 in Micro Drilling – Understand the Coolant

Micro drilling of rounded surfaces like the one shown in this photo requires a 4th axis solution.
Micro drilling requires research to understand the material being drilled and the available coolants.

The second step, after you do your homework and figure out the specifics on the material you are running, the coolant you are going to use and narrow it down to two or three drill manufacturers is to look at your program.  First and foremost, when you are programming a micro drilling operation is the drill cycle itself.  There is varying information available on the most successful strategy, but one thing everyone agrees on is that it has to be a pecking cycle.  A chip break cycle (where the drill does not retract fully out of the hole, only enough to break the chip) is generally ineffective because it leaves chips in the hole. On a standard drill the flute is carrying those chips up and out of the hole. Technically, micro drills will do the same, except you really don’t want them to.  Drills that small (.008” in my case) DO NOT like re-cutting chips and will eventually break because of it.  A full retract on every peck is the strategy I choose, and while it may take a little more time it is the best way to ensure the longest life of your drill. There are machinists (and tooling manufacturers) who will suggest a “chip break, chip break, full peck” strategy, which will be faster but I would only apply this at the upper end of the “micro drilling” scale.  This scale by the way is another point of contention.  A micro-drilled hole is generally considered any hole smaller than .1”, but you will always have people who disagree.  Call it what you will, it’s small.  Anyway, back on track.  Strategy is very important.  You want to make sure that the tool clears the hole with enough distance and time to clear the chip and receive some coolant.

Optimal Coolant for Micro Drilling

Micro drilling coolant shown cooling a micro drill (in comparison to a pencil tip).
In micro drilling coolant is a key consideration. Here a spray mist (minimum quantity coolant) sprays on a micro drill (shown in comparison with a pencil tip). Yes, we drilled the pencil tip … because we can!

Coolant.  It’s an interesting term – true to life, since it is actually cooling the tool, or at least acting as a vehicle for heat transfer.  However, in micro drilling the more important aspect is the lubrication.  Water-soluble coolants do a very funny thing that most people don’t realize when you’re drilling.  When the bottom of your hole fills with coolant and the tool enters the hole, it actually becomes pressurized.  Under normal circumstances this is not a concern, but with micro drills being so fragile it can easily be enough to overpower the tool.  I am using a misting system for my operation, along with a thin oil that flows well.  What happens is the oil pools on top of the part, so no matter what the drill passes through the coolant and lubrication before contacting the part. The only problem this presents is chips.  As you machine holes you notice chips building around the completed holes.  Due to the fact that the oil is not flowing like a flood coolant, it doesn’t carry the chips away.  This is currently a problem I am trying to remedy, but again it’s a very time consuming process that involves much patience … and frustration.  You will be OK.  Plan to break a few drills, and plan to try different things.  Just don’t plan on drilling a hundred holes in ten minutes.  Micro drilling is not, and should not be considered a high-speed machining operation.  It takes care and precision.

Optimal Tools for Micro Drilling

Micro Drilling Tools can be as small as this 0.0015" drill shown in comparison to a penny.
Micro drilling tools like this 0.0015″ drill (in comparison to a penny) require research, experience and the right CNC machine to use effectively.

Finally, I’m going to discuss a little about the actual tools.  There are many tooling companies that provide micro drills.  In your research you will find that many of them have very specific information on the geometry they use for their cutters and the coatings and every other bell and whistle you can imagine.  Do yourself a favor and pay attention.  Some of it may seem like fluff, which it may be, but some of it is very important.  If you have read any of my other blogs then you know that sometimes seemingly small things make all the difference.  Such is the case here.  These tools need to be precision ground and incredibly sharp.  As is the case with most aspects of micro drilling, there are differing opinions on the tooling material – carbide or high-speed steel.  While carbide offers better rigidity and longer sustainability of the cutting edge, high-speed steel offers more flexibility. Carbide is brittle and will break as soon as it’s dull – high-speed steel is more forgiving and lower cost.  It all comes down to the workpiece material.  This is another situation where I hand it off to the true experts – the ones who make the tools.  One last bit of advice on the tooling – don’t go cheap.  If you do your research and you find that you can achieve your goals with a $15 drill that’s fantastic. Just don’t shy away from a drill just because it costs $75.  The name of the game is value, and be sure to explain to your finance department that the best value doesn’t mean the cheapest drill.  If “Drill A” costs $15 and drills 100 holes, and “Drill B” costs $75 but drills 1,000 holes then the better value is Drill B, even at five times the cost.

I would give you an idea of some of the parameters I am running but that would essentially defeat the purpose of my post.  Do your research, find your numbers and run with it.  I have been very impressed with the success of the base parameters I have received from tooling companies, so always remember – trust in the numbers.

Download a Real-World Micro Drilling Case Study:

CNC Milling Laminated Shims

Milling laminated shim with a high speed CNC machining center featuring vacuum workholding and a 40,000 - 60,000 RPM spindle.

Let’s face it, some materials are just no fun. Inconel, hardened steels, ceramics. Everybody likes a material that will cut like a butter, and a typical dread is associated with stuff that doesn’t. So recently, we were presented with a material in the latter category. Milling laminated shims from stainless steel sheet stock.

Everyone we asked had a similar reaction. “Stainless shim stock? That stuff sucks.” And there were many reasons. Delamination during machining, enormous burrs, difficult fixturing. General misery.

Milling laminated shims out of stock like this laminated stainless steel sheet material is best handled using a high speed CNC milling machine with vacuum table workholding.
Milling laminated shims from stock like this laminated stainless steel can present some challenges.

So when addressed with this difficult task, I cringed a bit, and got to work. Luckily for us, DATRON’s technology is a perfect fit for machining shims. But why?

Vacuum Workholding is Ideal for Milling Laminated Shims

Your typical shim machining fixture looks something like this; A base plate, a layer of adhesive, a layer of shim stock, another layer of adhesive, then a sacrificial layer of aluminum on top to prevent delamination. Needless to say, setup takes a long time, and break down takes even longer. With our vacuum table fixturing, the setup is bit more manageable; the vacuum table, a layer of vacuflow sheet, then shim stock. Done. Probe the material and go to town.

CNC milling laminated shims with a high speed machining center equipped with vacuum table workholding for quick setup.
CNC milling laminated shims can be an easier process by using vacuum table workholding. This photo shows how it works.

High RPM Spindles for Reduced Chip Load When Milling Laminated Shims

With a typical VMC, RPM does not get too high. Maybe 10,000 RPM. The issue with this is the cutting forces being applied. Let’s consider a 1.5mm double flute end mill, cutting a part at 10,000 RPM, at 60 inches a minute. That ends up being a 0.003” chip load. That is a problem, and it’s also the reason delamination is so prevalent in shim machining. Cutting forces are too high. Using the same tool at the same feed rate, but at 30,000 RPM, we just reduced our chip load to 0.001”, bringing the cutting force down by 2/3. This is what allows us to cut the shim stock without a sacrificial top layer, thus saving time and aggravation.

Milling laminated shims using a 40,000 - 60,000 RPM spindle helps to reduce chip load which prevents delamination.
Milling laminated shims with reduced chip load is achieved with a 40,000 – 60,000 RPM spindle.

Milling Laminated Shims – Clean and Accurate

There are other methods of cutting shim stock, obviously. Some work better than others. Laser cutting can have issues with welding layers of material together. Waterjet can manage it, but the tolerances aren’t really there, requiring machining after the fact. This is where a DATRON can shine. With high speed machining, edges come out clean and burr free, and tolerances come in within 0.001” (over the work envelope). The benefits here are significant; remachining, cleaning, deburring, can be cut down tremendously, allowing you to move on to the next job.

Now that doesn’t sound so bad, does it? Next time you’re dealing with a problem child like shim stock, give us a call, we can help.

Learn more about vacuum tables – download the data sheet:

Machine Shop Math – Common Formulas and Strategies

Machine shop math blog detailing feeds, speeds and formulas associated with CNC machining and milling machines.

One of the more common problems I have seen in my years in the machine shop is a general lack of readily available and handy information on machine shop math – specifically on feeds, speeds and related formulae.

Machine shop math for feeds, speeds and other important aspects of CNC machining and milling applications.
Machine shop math is an important consideration for CNC programmers and machinists.

Whether you are programming a 5-axis CNC machine or turning handles on a 60 year old knee mill the numbers don’t lie.  However, one very important lesson I have learned is to respect the variables.  Any common formula you are going to use in the machine shop will provide you with the information you need to approach the cut appropriately but remember to always treat that number as a starting point.  There are an immeasurable number of variables with any cut, all the way down to the atmospheric conditions in the shop.  Tooling manufacturers will provide you with suggested numbers whether it be surface feet per minute, chip load per tooth, revolutions per minute, inches per minute or any combination of those and more.  It can all get very confusing and overwhelming but don’t quit on me now.  I am hoping this post can serve as go-to information for you and your shop, and hopefully I can make some sense of it for you.

Machine shop math formula for RPM, SFPM, Feed Rate and Chip Load per Tooth to help machinists and operators of CNC milling machines.
Machine shop math formula for SFPM, RPM, Feed Rate and Chip Load per Tooth.

As you can see in the above formulae in order to calculate any of these you need to already know some of the other data to input.  This is where the tooling manufacturers come in.  They can provide information to you for their specific tools and applications.  However there is some basic information based on the material you are cutting that I will provide to you right now.  Keep in mind that these are starting points, the best judge will be your eyes and ears.  The following is a list of suggested SFPM for common materials:

Machine Shop Math – SFPM for Common Materials:

Surface feet per minute parameters associated with particular millable materials.
Surface Feet Per Minute (SFM) parameters based on material.

So let’s say we are using a .500” solid carbide end mill cutting aluminum.  Looking at our chart the suggested SFPM is 800.  In order to determine our suggested RPM we use the above formula SFPM x 3.82 / Tool Diameter:

Machine shop math formula for calculating revolutions per minute (RPM) can be used by CNC machine programmers and machining center operators.
Machine shop math to calculate RPM (revolutions per minute).

I will give you another example, this time with a significantly smaller tool.  We are going to use the same material but this time with a .125” solid carbide end mill.

In machine shop math SFPM or surface feet per minute can be calculated using this formula.
In machine shop math SFPM is surface feet per minute and can be calculated with this formula .

You can clearly see where the tool diameter drastically changes the suggested parameters, and where a high RPM spindle is a valuable factor.  This table can be used for these common materials however the manufacturer of the tools you choose will most likely have specific information on the tools you purchased which should always be used when available.

Are you still with me?  I know, you feel like you are in high school algebra again.  All of these numbers will make more sense when you start applying them to jobs in YOUR shop on YOUR machine, until then stick with me!  I promise it will be worth your time.  We are going to move on to Inches per Minute.  If you reference the formula above Feed Rate (inches per minute) = RPM x Chip Load per Tooth x Number of Flutes you see that in order to calculate this you need tool information.  Chip Load per Tooth is the amount of material a tooth, or flute, of the tool is removing in one revolution.  Most tooling manufacturers have suggested chip load information available, but you can also use your own knowledge and expertise to make a suggestion.

In this example we are going to be using a .500” solid carbide end mill with three flutes to cut aluminum.  Since we already know from the first example that the suggested RPM is 6,112 all we need is the chip load per tooth.  The manufacturer suggests .005” per tooth chip load on this tool, so we have all of the information we need to calculate our feed rate.

Machine shop math inches per minute formula used by CNC machine programmers and operators.
Machine shop math inches per minute formula.

See?  That is not as confusing as it looked.  However, here is where some of variables come into play.  Serious consideration needs to be made for the type of cut you are performing.  If you are milling a slot with full tool engagement then you need to be more conservative.  However, if you are utilizing a dynamic strategy (as discussed in another blog post) then you could potentially be more aggressive.  As I stated in the beginning, these numbers are starting points.

Finally, we will discuss how to calculate Chip Load per Tooth.  This is a useful formula for both preparing for a cut or programming and analyzing an existing cut.  You can easily look at your program while trying to optimize either surface finish, cycle time, or tool life and this will be a good indicator of proper tool utilization.  Let’s say we were running that last example at 4,000 RPM instead of the suggested 6,112.  We also ran it at 120 IPM rather than 91.68 IPM.  Our results weren’t great and Quality Control wants answers… NOW!  I know!  Let’s check the numbers!


This is double the manufacturers suggestion, therefore a very good place to start looking for problems.  Using the formula that you have now mastered, you know that you either need to bring your feed rate down or your RPM up to meet the requirements.

Now that you are armed with a basic understanding of these formulae and the knowledge that NONE of this is set in stone, you are ready to start applying it to your everyday work.  You will be amazed how quickly you won’t need to reference any charts or websites to be confident in your numbers and the job of programming a very expensive CNC machine will become a little less stressful.

If you want to put these formulas to work using the best cutting tools of the market, just download the DATRON Cutting Tools Catalog by filling out the following form.

Download Cutting Tool Catalog:

Halftone Engraving on a CNC Machine

Halftone engraving of a DATRON M8Cube high speed milling machine that is actually made on the M8Cube milling machine.

When you get to work with a DATRON every day, you get to see some pretty cool things. There are so many cool things to observe, or be involved in, that you can become a little numb to just how cool these things are. So, every once in a while, it’s good to stop and look back at what you’ve been doing and take a second to appreciate it. In this case, it’s halftone engraving.

I thought this might be a unique topic to share with you, the reader, so you too can enjoy the cool things you can do with your CNC machine (hopefully a DATRON!).

What is a Halftone?

First, a little background on our subject. A halftone image, according to Wikipedia, is “the reprographic technique that simulates continuous tone imagery through the use of dots, varying either in size or in spacing, thus generating a gradient like effect.”

Halftone engraving is the simulation of a continuous tone image using dots that vary in size or distance.
Halftone engraving is a reprographic technique simulating a continuous tone image.

Essentially, the trick behind a halftone image is to use varying size dots to create a grey scale image. It’s comparable to some comic book printing or pointillism, but is a bit unique.

Halftone engraving using different size dots milled into the surface of blue sheet material (with a silver surface finish) to create a grayscale.
Halftone engraving on blue sheet material with a silver surface finish requires milling varying size dots to create a grayscale image.

Halftone Engraving Software (Free)

Now, let me introduce you to Halftoner, a free application created by Jason Dorie. It allows you to easily import any image and not only convert to a halftone image, but also apply a tool path to it at the same time. The elegance of this software comes from its simplicity; first, import an image and choose your values for minimum and maximum dot size, dot spacing, dot offset, etc… Then determine your milling values; retract height, minimum depth, feed rate, RPM, and so on. One of the most important values for Halftoner is the tool angle, since it will take the included angle of your tool to determine the necessary depth to make a certain size of dot. It’s really quite intuitive.

Once that’s all done, click “Write GCode” and voila, you’ve got a program ready to go.

Engraving halftone images with a DATRON high speed machining center and a free application called Halftoner.
Engraving halftone images with a high speed CNC milling machine can be done easily with a free application called Halftoner.

I was fortunate enough to get to play with this for a while on a recent project, and the outcome you get for a minimal amount of effort can be very impressive.

Engraving halftone graphics on an engraving machine requires the engraving of different sized dots that reproduce a graphic by simulating a continuous tone image.
Engraving halftone images is quick and fun using a high speed milling and engraving machine like the DATRON M8Cube.

Want more info on engraving? – Download Engraving Brochure

Hard Milling on CNC Machine

Hard milling of 63 Rockwell steel on a DATROn high speed CNC milling machine

The mention of hard milling is usually enough to give the average machinist/programmer anxiety.  Well save your Xanax friends, because hard milling is not as scary as you think.

There are many factors involved with successful hard milling and I am going to touch on them today.  My hope is that you will take the information I give you today and go learn even more.  The best thing you can do in approaching any hardened steel is educate yourself before you cut a single chip.

Hard milling steel like this 63 Rockwell 6,000 RPM, 100 inches per minute at .012 per pass (ramping)
Hard milling steel – 63 Rockwell, 6,000 RPM, 100 inches per minute at .012 per pass (ramping).

The first and probably most important consideration in hard milling is the construction of your machine.  In order to achieve ideal results with hard milling you need an extremely rigid machine that has a high degree of dampening ability.

Hard milling CNC milling machines require rigidity that can be provided by a machining table made of granite or concrete polymer.
Hard milling CNC machines require rigidity provided by polymer concrete or granite machining beds and cast steel construction.

Generally, machines constructed with polymer concrete have many times the dampening ability as machines made with cast iron. It is also important to have a CNC control that will handle the dynamic requirements of the constant and rapid acceleration and deceleration.

Hard milling machine with a solid granite machining table provides the rigidity needed for milling hardened steel.
The thick solid granite machining table on the DATRON M10 Pro makes it a rigid hard milling machine.

Next on the list is the spindle and tool holding.  Two very different things, but if one is off the other won’t matter much. You need a rigid spindle capable of high RPM with very little runout.  If your spindle has runout then the most concentric and true tool holder in the world will only help you so much.  That being said, combining a great high speed spindle with the best tool holders will yield results you never thought possible.  HSK series tool holders are probably one of the most popular in terms of hard milling because the interface with the spindle promotes great rigidity and concentricity.

Hard milling spindle and HSK tool holders exhibit both rigidity and low runout for superior results in machining hardened steel.
Hard milling spindle and tool holders should be selected based on rigidity and low runout. We’ve found the HSK tool holding system to be extremely effective.

Of course we cannot forget tooling itself.  If you do a little research you will find there are many tooling manufacturers who make application specific tooling for hard milling.  I tell my kids all the time that I know everything, unfortunately I don’t think you are quite so gullible. The majority of these tooling manufacturers have experts who can assist you in selecting the tool for the material and specific cut you are making, and I suggest utilizing those services.  The cutting tools you choose for your hard milling applications will need to be coated to stand up to the high heat and extremely high abrasive forces involved with these materials, so take your time and learn something.

Also, the tools will most likely not be cheap, so don’t be caught off guard.  DO YOUR RESEARCH!  If you bring a purchase request to your boss and he chokes on his coffee because the end mills you are buying cost so much, you will be able to throw so many big words at him to justify the purchase that he will have no choice but to sign it.  Also, if you need two make sure you request four.  That way when he authorizes the purchase of only two he feels he saved the company money and he can puff out his chest while you get what you wanted in the first place.  Tried and true techniques, this isn’t my first rodeo.

Hard milling tools including the 8mm 4 flute end mill, 0.5mm edge radius with x.ceed coating from DATRON perform extremely well and last longer
Hard Milling Tools like this DATRON 8mm 4 flute end mill, 0.5mm edge radius with x.ceed coating exhibit superior performance and extended durability.

OK, back to business.  The final piece of the puzzle (not really, the puzzle never ends…) is the CAD/CAM software.  One of the most important considerations in hard milling is a programming software that can control the load placed on the tool.  You want a constant load on your cutting tool without spiking, which means trochoidal milling is in order, or as I usually call it, dynamic strategies.  The principle behind dynamic milling in relation to hard milling is the light, constant engagement of your tool into the material.  No sharp plunges, smooth constant force.  Most of the major CAD/CAM packages out there now have some form of dynamic milling.  For more specifics on dynamic strategies see my recent blog post on the subject.

Hard milling program developed with the appropriate CAD/CAM software for the effective machining of hardened steel
Blog author, Kevin Mulhern, the qualities in CAD/CAM software required for an effective a hard milling program.


As with anything you do in the machine shop, or garage, or anywhere else you are using these tools and strategies, KNOWLEDGE IS POWER.  Research, study, ask the old guys, google it – whatever you have to do, the name of the game is learning. The more you know heading into a challenge the easier it will be to overcome it.  Good luck in your first steps into the world of hard milling- it will open your eyes.

Need Tools for Hard Milling? – Download Tool Catalog

6 Easy Ways to Optimize CNC Program

Optimize CNC Program with tips and directions provided by DATRON Applications Engineer Dann Demazure in this blog.

“Optimize CNC Program” – it’s the instruction you hear in your head when you’ve finished a machining program. And it can be an arduous process that, if you’re like me, you slave over. Typically a bit too much, wasting a lot of time on changes that don’t add up to a substantial improvement. As we all know, time is money, so, I’ll try to relieve you of some of the labor of revamping your program. Here’s a list of quick, easy, and effective tweaks for your DATRON programs.

Optimize CNC program tips and detailed instructions in this blog by Dann Demazure from DATRON Dynamics.
Blog Author and DATRON Applications Engineer, Dann Demazure, optimizing a CNC milling program.


Optimize CNC Program Tip 1 –  Leave the coolant on

It may not sound like much, but this gain can really add up. If you’re using coolant in your program, consider switching it from the Positioning/Cutting feed setting from Cutting <0>, to Travers<1>. You may not easily perceive it, but there is a very brief dwell programmed into the software so that the coolant has time to begin spraying. This change in the command will leave your coolant spraying between positioning movements, thus avoiding the initial dwell. Now, each dwell may only last 1/10th of a second, but if you have 200 retracts in your program, you just shaved 20 seconds of your program, and that’s not nothing.

Optimize CNC program by leaving the coolant running during positioning movements to avoid the initial dwell.
Optimize CNC program by leaving the coolant spraying during positioning movements.


Optimize CNC Program Tip 2 – Ramp

If you’re cutting along a contour, consider changing your method. If you are currently doing depth cuts, try a ramp instead. A ramp keeps the tool engaged in your desired amount of material throughout (except for the very beginning and the very end), and has no retracts. Let’s say again that your part has 200 retracts cutting contours on 20 different features (10 retracts per feature). By ramping, you’d bring that number down from 200 to 20 (final retract), and if each retract takes half a second, you just saved 90 seconds.

Optimize CNC Program Tip 3 – Be smooth

If the devil is in the details, then small contours are your devil. If you’re doing intricate engraving or 3D contouring, then you’ve probably noticed that the machine will slow down to follow all contours tightly. It’s just following orders, but if you have a little leniency in your adhesion to contours, Smoothing can make a huge difference.

Optimize CNC program with smoothing functions to clean up jagged geometry for a tighter milling path.
Optimize CNC programs using Smoothing functions like PerfectCut to smooth jagged geometry. See the results in red above.


Smoothing will take jagged geometry, like what is pictured above (purple), and apply arcs to the contour to create a smooth, more continuous motion (red). Not only does this have benefits for surface finish, but since the machine doesn’t need to slow down nearly as much in an arc as compared to a vector, time savings can be abundant. And utilizing it is as easy as writing the code in your macro, editing the preset values (which work well for most things), and pressing the “Go” button.

Optimize CNC Program Tip 4 – Be dynamic

I’ve talked about dynamics at length before and all the benefits from using them to fine tune a process for speed optimization and ideal surface finish, so why am I mentioning them again? Easy, besides the fact the dynamics settings are one of the easiest ways to reel in cycle time, adjusting them in conjunction with smoothing yields even better results. A high dynamics setting combined with a smoothing filter means that a very minimal amount of deceleration is needed to turn a corner quickly, thus cutting your cycle time even further.

Optimize CNC Program Tip 5 – Get low

This is usually a gimme, but it takes about 10 seconds of your time to change your retract heights from 0.5”, to 0.050” (or lower). Minimizing your retract height won’t save you much time per retract, but think of the big picture. Even if you only saved 5 seconds per part, if you’re making 20,000 parts per year, you just saved over a day of machine time. Every second counts.

Optimize CNC Program Tip 6 – Keep your tools in order

It seems obvious, but try to keep your operations organized so that when a particular tool is done, it never gets used again in the program. Sometimes this is unavoidable, but each tool change will cost you somewhere around 15 seconds of time. Consider using combination tools to cut down on tool changes. Most importantly, if you have parts nested, use tools sequentially rather than by part. If you have to cut 24 parts, and each part uses 4 tools, you’ll either spend 24 minutes changing tools again and again, or 1 minute changing all the tools once.

If you’d like more information on the PerfectCut Smoothing mentioned in Tip 3, Download the Data Sheet by filling out the form below:

Download Optimizing CNC Program Smoothing Tip #3 Data Sheet

Machine Shop Career: Where Do You Start?

A machine shop career can offer a breadth of experience with diverse projects and processes.

There are very few things that you can look at today that has not passed through a machine shop on some level.  Therefore, a machine shop career can be both interesting and rewarding. 

A machine shop career can bring on projects as diverse as F18 ejector seats and swizzle stick molds.
Just a few of the parts that may present themselves in the span of a machine shop career. Can you spot the F18 ejector seat part, the knife handles or the swizzle stick mold?

Answers:  F18 Ejector Seat  |  Knife Handles  |  Swizzle Stick Mold

I am sitting in a hotel room right now so let’s look at some examples.  This laptop, my cell phone, the remote for the TV, the TV itself that’s allowing me to watch Monday Night Football right now, the microwave, the trash barrel – all of these things have parts that are molded.  All of these molds require machining. The desk chair that I am sitting in right now has machined parts.  The rental car out in the lot has too many machined parts to name.  The knobs on the bureau, the lamps, the alarm clock.  OK, you get the point.  In my machine shop career I have worked for two tool and die shops that made molds for plastic injection molding; I worked in a maintenance machine shop for a power company that machined 8’ diameter pump housings and 27’ long pump shafts along with map brackets and any other parts the field techs needed; I worked for a company making parts for benchtop educational milling machines;  I worked for a machine shop that machined nothing but man-made sapphire (interesting stuff by the way);  I worked for a company that produced bridge and communications systems for the U.S. Navy, and I worked in a machine shop that made parts for commercial printers.  I also did a short stint in a standard job shop.  I know, I know you get the point.  I just love talking about myself.  My point is that no matter what your interests are you can find a shop that takes part in the finished product.  There are so many different machine shop career paths available to anybody willing to get their hands dirty and deal with a sliver or two.

A machine shop career lead Kevin Mulhern to DATRON Dynamics where he now works as an application Engineer
Kevin Mulhern’s machine shop career lead him to a position as an Application Engineer for DATRON Dynamics where he helps some of the world’s greatest manufacturers optimize their machining processes.

Machine Shop Career – How to Choose Your Path

My first piece of advice is HOLD YOUR HORSES!  No matter what path you want to take and no matter what vision you have of your machine shop career do yourself (and your future coworkers) a favor and start with the basics.  I will be writing another blog in the near future that will explain some of the basic things you will see and experience in the machine shop.  So at the very least when you walk out there with your clean hands, nicely ironed khakis and goofy looking safety glasses you can hold an intelligent conversation with the old barnacle behind the engine lathe.  Your first stop on the path to your machine shop career should be one of two places – a machine shop program at a technical college or an entry-level job in a machine shop that is willing to teach you the trade.  As soon as I graduated high school I entered an apprenticeship program which paid my tuition at the local tech college.  You can’t all be as cool as I am, and that’s OK … I set the bar high.  The fact of the matter is this is one situation where you want to start from the ground floor.  There are so many things that you need a firm understanding of before you can be a competent machinist that you won’t get by skipping past the basics.

One thing you will discover quickly is that there is no substitute for industry experience.  That is not unique to the world of machining, but since this is a machining blog I don’t care.  School will teach you many of the skills you need to succeed, but it’s that grumpy old bastard who hates his job that will polish you to a high sheen.  The industry right now is in desperate need of KNOWLEDGABLE machinists.  Go through school and sharpen your skills on the engine lathe, Bridgeport and bench grinders (as well as hobbs, drill presses and broaches) for a while … and THEN it’s time to really choose a path for your machine shop career.

Manual vs. Automated in a Machine Shop Career

There are many different directions to go.  For the longest time I preferred manual machining.  My abilities and knowledge on the manual machines afforded me respect from the old timers that a lot of my young counterparts never enjoyed.  It allowed me to truly decide what I WANTED to do and where I wanted that to bring me.  I know what you are asking yourself … and no, I didn’t put all those years in so I could write these fantastic blogs.  This is just the icing on the cake.  You’re welcome.  Really though, once you build a solid base the sky is the limit.  You can stay in manual machining, it is a dying breed and pretty soon will probably earn as much or more than a CNC programmer.  None of the young kids want to turn handles anymore, and it really is a shame because the best programmers are the guys who never wanted to program.  You can specialize in CNC lathe, swiss screw, CNC milling, four or five axis milling with live tooling.  There is so much new technology out there that you will never run out of new things to learn.  You can go towards engineering in CAD/CAM design, you can program as we have discussed, and you can start as an operator and earn your way up the ladder.  The machining world is your metallic oyster.

As usual I ramble.  I love this stuff, I can’t help it.  I hope that you can follow my advice and find yourself in the same position.  In short, put your time in.  Learn your trade.  Build a good base and there will be nothing standing in your way.  Don’t sell yourself short, just trust in the numbers.  I promise they don’t lie.

If you want to study up on the greatest of all CNC machines (again I’m biased) download this brochure:

Download DATRON CNC Milling Machines Catalog:


Machine Shop Jobs – Why Work in a Machine Shop?

Machine shop jobs can be very rewarding and in this blog, Kevin Mulhern explains how to get started and where it brought him in his career

Perhaps you are trying to decide what you want to do when you grow up.  Or maybe you are looking to change your career path.  It really doesn’t matter why you are here, I just hope that maybe I can convince you to consider a move into one of the most progressive and exciting industries out there – machine shop jobs.  When I was in high school and trying to decide between auto mechanics and machine shop, my father suggested the machine shop because it was something he had done and there were lots of machine shop jobs available.  Well, I didn’t have any idea what machining was say nothing of CNC machines and I had no interest.  I signed up for auto shop instead.  Fortunately for me, the class was full and I was forced into the machine shop class.  After the class started it did not take me long to fall in love.  However, after I finished high school,  trade school and an apprenticeship program, it seemed as though all the machine shop jobs had dried up.  So here’s my first bit of advice … don’t base your future on now.  It’s not an easy thing to comprehend when you are young, but just because there are jobs available now doesn’t mean there will be in five years.  So, find something that you love to do, can do well, and can make a career out of.  Sometimes easier said than done, but if you love what you do you will find a way to make it happen.

What’s so great about machine shop jobs?

Clearly, I am biased.  I think I am in the greatest industry in the world.  With machine shop jobs there is endless variety, always something new to learn, and while production might go overseas there will never be a day that a good machinist is not in demand.

Machine shop jobs led blog author, Kevin Mulhern, to a successful career as an Application Technician helping some of the worlds biggest manufacturers to optimize their manufacturing processes.
It all started with a couple of machine shop jobs and now I’m an Application Technician helping some of the biggest manufacturers in the world to optimize their production processes.

There are very few things that you will be able to find in your immediate surroundings that have not been through a machine shop somewhere in the production process.  Even the plastic toys that your kids play with, or the water bottles your favorite player drinks from have been through a machine shop to produce the mold, which in turn produces the final product.  No matter what industry interests you the most, somewhere along the line there is a machine shop job that directly supports that industry.  Here’s an example video below … ever wonder how radio-controlled drones (quadrocopters) are made?

What’s it take to qualify for machine shop jobs?

No matter what interests you – whether it’s getting your hands dirty, math, or computers – there is a solid career waiting for you in the machine shop.  Manual machining requires not only mechanical aptitude, but a steady hand, and a good eye.  A good manual machinist is becoming difficult to find, which is why finding a decent paycheck as a manual machinist is not too difficult.  CNC programmers and QC inspectors tend to be math heavy.  Don’t get me wrong, math is a vital part of working in any capacity in the machine shop, but as far as crunching numbers and putting those numbers to action programmers take the cake.  Any time you delve into the world of CNC machines, a comfort with computers is important.  Since CAD/CAM packages are PC based and many CNC controls have also moved that direction there is no getting away from it.  If you enjoy computers, have an affinity for math and don’t mind getting your hands dirty, you will never be out of work for long.

There seems to be a growing trend lately, though it’s more like a return to old practices where companies are starting to hire with less experience and complete on the job training.  This makes it a little easier to get a job in a shop since they aren’t going to require ten years of experience and an associate’s degree just to get your foot in the door.  It might take a little longer to climb the ladder to the higher paying jobs, but it certainly opens doors that weren’t open when I was breaking into the industry.  Keep an open mind, always stay hungry for more knowledge and work your ass off … you will have a long and prosperous career in the machine shop.

If you want to study up on the greatest of all CNC machines (again I’m biased) download this brochure:

Download DATRON CNC Milling Machines Catalog:

Bulk Material Removal CNC Milling Strategy

CNC bulk material removal with high speed machining center at 35,000 RPM using a single flute end mill and a helical milling strategy

When it comes to CNC milling strategies for bulk material removal you may be asking the wrong question.

As the account manager for industrial CNC sales in the Northeast USA, I routinely get asked, “What is the biggest tool you can put in a DATRON machine?” And while I always take time to answer this question, it gives me a bit of a chuckle because DATRON high speed CNC milling machines are all about efficiency with small tools! Now, of course I understand that in spite of the fact that this equipment has huge headroom in the RPM department, it must at the same time be capable and efficient when it comes to milling out larger features and bigger parts – most of our equipment does after all have a work envelope of 30” by 40” – but in the world of high RPM and high speed cutting strategies large features or bulk material removal does not necessarily warrant a large diameter tool.

An easy example is the simple process of pocketing: taking a workpiece and milling out an area to create an open space. In this example we’ll assume the pocket is to be 0.75” deep by 2.75” wide by 7” long. Traditional machining methods would involve the use of something on the order of a 1” diameter end mill making a traverse path along the length of this part with standard step down and step over values at typical RPMs of less than 15,000.

Bulk material removal with a CNC milling machine can be effectively performed with smaller tooling using a high speed spindle and a spiral (helical) tool path.
Bulk material removal can be done effectively with small tools using a spiral (helical) tool path and high RPM rates.

In the world of high speed cutting and new school cnc milling strategies, a more efficient toolpath can be realized by use of a comparatively small tool, such as a 6mm end mill, and beginning with a helical toolpath that circles all the way down to the final depth. From there, a large percentage of the cutting flute can remain engaged in the material as the tool circles around removing material continuously as it widens it’s circular X/Y path until the full pocket has been created. This type of strategy, when combined with the right RPM and cutting tool geometry, can outperform a physically larger tool that is using lower RPM and traditional strategies.

Milling bulk material removal or dynamic roughing in high speed CNC milling can be performed with a single flute end mill using a helical strategy and high RPM around 35,000
Bulk material removal area (or dynamic roughing) represented in orange done with single flute end mill using spiral pocketing strategy and full Z infeed.

To summarize, in the world of high speed machining it’s all about making a lot of small chips very quickly. The necessity of a dimensionally large tool to create a dimensionally large feature have been eclipsed by the advent and proliferation of high speed milling machines with the CAM strategies and cutting tool geometry to go along with them.

For more information on the CNC Milling Strategy used on the aluminum housing shown above:

Download CNC Milling Strategy Application Notes with Bulk Material Removal (Aluminum Housing):