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):

CNC Workholding for Milling Machines

CNC Workholding for milling machines and machining centers that reduce set up and job change over times.

DATRON_Workholding_Solutions from DATRON Dynamics on Vimeo.

In the world of manufacturing, specifically machining of material, there is an art to proper CNC workholding.

You may have the concept and design of a valuable product or part, the program skillfully complete with the optimum machine and material.  But if you do not have a means to hold the material during your process, rigid throughout all surfaces and vibration free, the race is lost.  “A horse, a horse! My kingdom for a horse!”  This quote is fully understood by every machinist, tool and die maker, Production Cell Supervisor, Project and Plant Manager.  Nothing will stop a successful process in it’s tracks like material poorly held causing tool breakage, material slip, high scrap rates, possible machine damage and worse, potential operator injury.  A fixture, a fixture my process needs a fixture!

At DATRON we have heard this cry many years ago and sought solutions to be used with our machines for the many varied process requirements that the DATRON machine is used for.  These had to be versatile, minimal labor requirement for use, repeated usage, allow accuracies to match the DATRON machine and like the DATRON machine provide thousands of hours of reliable use.

Another great benefit of using tested CNC workholding with your DATRON machine is the savings of time and material loss.  Once you have optimized your product, program, material and machine process the last element to review and add profit margin points to your product is time.  Operator time lost while loading and unloading the machine.   Increased scraping of product due to slippage. The loss tool rate or shortened tool life requiring operators to change tools prematurely.  These are all examples of time cost/time loss occurrences that translate to dollars lost. The end loss could be in cents or dollars per part but multiplied by the number of parts could very well be a significant amount of money making or breaking the production project.  The reduction or elimination of these occurrences will reduce the loss or add profit margin points to your end result.

I would like to introduce the CNC workholding royalty to augment the DATRON machines:

T-Slot Tables

T-slot CNC workholding segments can be secured on the bed of a DATRON high speed machining center and can be equipped with a multitude of clamping devices.
T-Slot table CNC workholding mounts to the machine bed and can be equipped with wedge clamping or short stoke pneumatic clamps among other solutions.

Work Pallets

Work pallet CNC workholding systems can be custom configured and use a boss in cavity method to make sure you hit the right spot every time.
Our work pallets or QuickPallets are one of our CNC workholding solutions that are are keyed using a beveled boss-in-cavity system to insure location repeatability.

Wedge Clamping Elements

Wedge clamping CNC workholding units add functionality to T-slot tables and allow for adaptable setup.
The wedge clamping CNC workholding units can be configured for single as well as for multiple clampings. Due to their clamping screw and the T-nut, they can be flexibly used on the DATRON T-slot plate.

Compact Centric Clamps

Compact centric clamp CNC workholding is protected from chips and debris through a special slide geometry that helps prevent particle build up and malfunction.
The compact centric clamp is completely protected from dirt, chips and debris. Due to special slide geometry with a guide length of 150 mm, the KZS is the first fully encapsulated centric clamp.

Pneumatic Clamps: Short stroke, positional

Pneumatic short stroke and positional clamps used in conjunction with T-slot tables as CNC workholding on milling machines.
Pneumatic Clamps (short stroke and positional) are smart time-saving elements used when flexibility and short cycle times are required.

Pneumatic Vertical Clamps

Pneumatic clamp system is CNC workholding that integrates onto the bed of a milling machine or machining center to shorten set up time.
Pneumatic clamping systems are an example of CNC workholding solutions offered by DATRON to help reduce setup times.

Vacuum Chuck, Vacuum Table

Vacuum table CNC workholding solutions are integrated on DATRON high speed milling machines and allow for quick setup of sheet material from 0.001" to 0.250" thick.
Vacuum table CNC workholding is designed to swiftly and efficiently secure flat workpieces to the bed of a machining system. Thin stock, which could be secured only with great difficulties before, is now secured literally within seconds. Quickly secure plastic foils as thin as 0.001”, to 0.250” large aluminum sheets.

Precision Rotary Axis

Precision rotary axis CNC workholding adds 4th axis functionality to DATRON high speed CNC milling machines.
Precision rotary axis CNC workholding for 4-axis functionality on a standard DATRON milling machine.

Precision Rotary Axis with Tailstock

This precision rotary axis with a tailstock can be integrated on the CNC milling machine to add 4th axis workholding and machining capability.
Precision rotary axis with tailstock used to add 4th axis capability to DATRON milling machines.

Rotary Swivel Table (Trunnion 5 Axis)

Rotary swivel table CNC workholding or trunnion 5-axis rotary axis used in conjunction with DATRON high speed machining centers.
Rotary swivel table CNC workholding a.k.a. Trunnion 5-axis system mounts in the cut away portion of the machining bed on a DATRON machine.


Pick n Place System (Automation)

Pick and place CNC workholding solution is highly customized and automated based on the user's specific part and application.
Pick and Place CNC workholding solutions are custom configured based on both part type and application. Pallets hold blanks and automated arm moves parts to a fixture for milling and returns them to the pallet after milling is completed.

In the coming weeks I will discuss each of these products, description and use.  Each of the above products have the DATRON “Test of Time” for versatility and longevity of use.  When used properly they can achieve perfect holding with production labor time/material loss savings adding profit margin points to your process.

For more information on these Workholding Options, download our Accessories Catalog.

Download Accessories Catalog:

Climb Milling vs. Conventional Milling

Climb milling vs. conventional milling is a common question among machinists. Both have their own advantages for example climb milling offers a superior surface finish while conventional milling can be more suitable when machining cast iron or hot rolled steel.

As a machinist you hear lots of technical terms getting thrown around. The old guys call it one thing and the young guys call it another. If you are not a machinist or are just entering the world of machining this can be confusing. Today I am going to discuss two of these confusing terms – climb milling and conventional milling.  Knowing the difference between the two and the proper application can set you apart from your peers and bring your overall part quality to the next level.

First things first, let’s set some ground rules. We will be running our spindle forward (clockwise) and using a standard end mill – we’ll get into down-cutting end mills and many other tooling options in a later blog post. For now, we are going with standard tools and we will go through the benefits and drawbacks on both manual and CNC machines.

With the tool rotating clockwise climb milling goes WITH the rotation. Think of the flutes, or teeth of the cutter as pulling the material, or CLIMBING through the material. When climb milling the flute hits the material at the top of the cut, and the thickness of the chip decreases as the flute cuts. This results in the chips being deposited BEHIND the cut, which is important. The chips clear the cutter, which means you are not re-cutting chips. Since you are not re-cutting chips, the result is a better surface finish and longer tool life. Less power is required from the spindle to climb mill, and the result of the cut is down-force on the material, which can simplify workholding considerations. Also when finishing the floor of a feature or face milling thin material the down force can assist in stabilizing the part.

Climb milling vs. conventional milling is determined based on the machining application and the advantages and disadvantages of both milling strategies.
Climb Milling – chips are evacuated behind the cut, so that you are not re-cutting them which results in a better surface finish.

There are however downsides to climb milling, the most severe of which will be found on manual machines. When performing a climb mill on a 60 year old Bridgeport you can run into some serious issues with backlash. Due to the pulling action of the tool on the material if you are using a machine that has a good amount of backlash the tool will grab the material and the table will move whatever distance that backlash is – on some machines this could be not only disastrous to the part, but incredibly dangerous to the machinist. Tool deflection (which we will cover in another post) with a climb mill will be perpendicular to the tool – so away from and into your part which will affect the thickness of your chip and potentially compromise your accuracy.

With the tool rotating clockwise conventional milling goes AGAINST the rotation. The flutes of your cutter are hitting the material and pushing against the rotation, depositing chips IN FRONT of the cut.  As expected, that will result in re-cutting of the chips which will both increase tool wear and decrease surface quality. Since the tool hits at the bottom of the part and the flute cuts upward with the chip getting heavier as it cuts, you are creating upward force on the part which can cause workholding issues.

Conventional milling vs. climb milling is the topic of this blog and advantages and disadvantages of both are discussed.
Conventional Milling – offers a significant benefit when machining hard materials like cast iron or hot rolled steel.

Just as there are downsides to climb milling there are upsides to conventional milling. When machining things like rough cast iron, or hot rolled steel, conventional milling is the preferred method. Especially with hot rolled steel due to the hard black layer on the outer surface. Performing a climb mill on hot rolled steel can result in chipped cutting edges because of the hardness of that outer layer and the more aggressive way the tool engages the rough surface, causing more deflection and potentially heavier chips. Since the tool deflection with a conventional mill tends to be parallel to the tool, it engages the rough surface at a more forgiving rate. Another strong suit of conventional milling is on finish passes. If you rough your profile with a climb mill, which will give you a good surface finish to begin with and then switch it up on the finish with a light conventional mill you will be surprised by the results. Due to the tool deflection seen with climb milling the conventional mill finish pass will give you a good finish on a light pass. Another option is a “ghost pass” or “spring pass” which is a cut in the opposite direction, in this case conventional, without actually taking a heavier cut. You will see the amount of material being removed, which was left by the tool deflection and it will leave a great finish as long as you lubricate.

Hopefully I clarified the issue of climb milling vs. conventional milling for you at least a little bit.  Both are useful strategies when applied in the proper situation. Always remember, when it comes to machining it’s the small details that make all the difference – no matter how small they may seem.

Learn More: Download the DATRON Cutting Tool Catalog:

How to Machine the End of a Long Part with Vertical Clamping

Vertical clamping for CNC machining on the end of long parts such as aluminum extrusions, enclosures and housings using a pneumatic clamping system integrated on a DATRON high speed milling machine.

It is always a challenge when faced with a long part that requires machining on the end or ends. Equally challenging is when you have to machine the side of a large part. Unless your facility is equipped with a machine tool that is large enough to mount such a part within the working volume above the machine bed, you are pretty much out of luck. Even if you have a machine that is physically large enough to accommodate the over-sized part, often securing or mounting the part can be very challenging. Traditionally any gantry-style machine or router-style machine would immediately be disqualified due to the limited clearance under the bridge. Unless that machine is a DATRON M8Cube.

The German-engineered gantry style M8Cube has a machining area of 1,020mm (40”) x 830mm (32 ½”) x 245mm (9 ½”). This is a good solution when having to machine large, precision parts not larger than 9” tall or deep. What if you are faced with a large mold or electronic housing that is 12” tall? The M8Cube offers an open area in the front portion of the machine table that allows you to mount taller parts that would not normally fit under the gantry. This is sort of like a trap door opening with vertical mounting holes on the front face of the opening to securely mount your over-sized parts. Often parts can be mounted while still remaining within the machining area. You could even mount a long extrusion (for example 36” long) vertically within this open area with the end slightly above the table surface. This allows you to keep the end of the extrusion to a minimum above the clamp, reducing vibrations in the work piece. Now all you need to do is machine the end of the part while the rest of the linear piece extends far below the table surface. This is a unique feature that is built-in to their standard machine. This feature offers a lot of flexibility and diversity for the job shop that never knows what kind of project they will be facing next.

Pneumatic vertical clamping system for securing long or tall parts that need to be machined on the end.
Pneumatic vertical clamping system for use in the “cut-away” area available as an option on many DATRON milling machines.

DATRON also offers a unique line of pneumatic vertical clamping systems to make it easier to mount linear or over-sized parts within the open area. These vertical clamping systems were designed specifically for the M8Cube open area. The work holding solution quickly mounts to the M6 threaded holes located on the front face of the open area. This vertical clamping system is pneumatically driven for quick clamping and release of work pieces by the touch of a button. For parts that have a short cycle time, this vertical clamping system is ideal because a part can be removed with a new part inserted and clamped again within seconds. You can also devise your own vertical clamping system and mount it to the provided mounting holes.

Vertical clamping system on a DATRON ML-1500 high speed CNC machining center is used as workholding for long or tall parts such as aluminum housings and enclosures that need to be machined on the end.
Vertical clamping system integrated on the front of the machining bed on a DATRON large format milling machine.

If you are faced with an unusual work piece that cannot fit in your conventional CNC machine, we would be happy to consult with you to see if this unique, simple design accommodation could be the answer to your most challenging part.

Download the DATRON Pneumatic Vertical Clamping System Brochure:

In Their Own Words – Engraver, DC Graphics – Talks DATRON Milling & Engraving Machines

Engraving brass embossing dies is an application that benefits from the integrated vacuum table on DATRON high speed CNC engraving machines.

DC Graphics, founded in ’94 by Kevin Brandon, is run today by Eugene Prohaske, President, and Kristine Brandon, Vice President, and has a long history in the engraving industry. Eugene is a passionate engraver and has over 30 years of experience in the engraving for packaging industry. He originally started in the engraving business with his father’s company, Styleart Engraving back in 1983. After his father retired in 1994, Eugene started his own business, HAP Engraving in Manhattan, together with a partner. They were in business until 2010 when he came to DC Graphics. Eugene originally joined business with Kevin Brandon, former President and original founder of DC Graphics. They worked together for about three years before Kevin passed away in 2013.

Engraving machine made by DATRON in Germany is used by DC Graphics to engrave plates, stamps and dies for the graphic packaging industry.
DATRON engraving machine used by DC Graphics in Farmingdale, NY to engrave plates, stamps and dies for the graphic packaging industry.

DC Graphics is an offset, flexographic pre-press, plate/die making and photoengraving facility, which produces magnesium and copper plates/engravings as well as CNC milled brass plates. DC Graphics, specializes in producing sculptured embossing dies and engravings, flat stamping and folding cards for the paper packaging and pre-press industry. They employ a staff of approximately 16 people.

Magnesium is a metal plate that can withstand high temperatures and is impact resistant as well.  Embossing and foil-stamping both require a plate that can meet these criteria for long press runs. Magnesium plates are also used to make rubber plates, signs and name plates; a versatile product indeed. Its durability provides the end user with a long-lasting printing image or die. Plates come in different thicknesses: 16 gauge, 11 point, and 1/4′.  The largest size is 18″ x 24″.  Copper is also used because it is a harder metal that lasts and stores longer for a better quality product. Counters for their embossing and debossing dies are available in both .030 and .060 thicknesses. They can also create fast and accurate brass dies to a customers’ exact specifications with CNC machining.

Known for engraving embossing dies, DC Graphics uses a DATRON CNC engraving machine for their work in the graphic packaging industry.
DC Graphics is known for engraving embossing dies like this intricate butterfly engraved on their DATRON machine.

DC Graphics is constantly seeking new innovations and utilizes the most current technology in its industry.  Having access to the latest technologies keeps DC Graphics ahead of their competition by allowing them to work more productively. Their state-of-the-art equipment allows them to provide their clients with high-quality products faster and less expensively than their competition. Before DC Graphics purchased their first DATRON high-speed milling machine, everything was done by hand, gauging machines and etching. But etching proved to be dirty and carried additional costs associated with disposal of the chemicals used in the process. They knew that they needed a change.

So, in 1996, DC Graphics purchased their first DATRON machine (an M4) and made a transition from everything being done by hand, gauging machines and etching and began using CNC milling machines. It was a big undertaking but proved to be a smart decision for DC Graphics to go green and DATRON was the perfect solution for that.

Prohaske says, “Once I saw everything, I decided this was the wave of the future for us and if we didn’t make the change when we did more than likely we wouldn’t been in business anymore.”

Engraving brass dies that produce graphic packaging for Yves Saint Laurent is and application performed on Datron CNC engraving machines by DC Graphics in New York.
Here you can see how engraving brass dies translates to graphic packaging for Yves Saint Laurent.

In 2008, DC Graphics purchased a DATRON M8 high speed milling machine, followed by and two additional M8s (in 2012 and 2013) to get their engraving jobs done quicker and to handle more business for their customers.

According to Prohaske, “At the beginning it was a big learning curve because we needed to get the machines in and had to figure out how to run them. DATRON definitely walked us through it as a real partner would do.”

It was a natural progression of having one machine and getting a second one soon. At this time, they had one DATRON and one LANG.  They took one year to evaluate the two machines and started weighing the pros and cons of both machines.  Both are reliable and good German-engineered machines, but the service and support in the U.S. provided by DATRON Dynamics was a major part the decision to get more DATRON machines.

“They are in the States and whenever I have a problem, they help me and respond to an issue right away. Having a contact person and service over here is key because if I need a part or help figuring out what the problem is or what needs to be replaced, I can get the part the next day; worst case scenario being two days.” says Prohaske.

Prohaske continues, “I always have good experiences with DATRON. They always treat me with a lot of attentiveness and they always help me to get through an issue and give me guidance. I respect that and know I can trust them!  Moving forward with the business and growing by getting more machines, it was just a logical decision to continue with DATRON. For what we need, DATRON is the best machine. The machines work fantastic because they’re very versatile and don’t break down. They last for years.”

Now, DC Graphics uses the DATRON machines for most of their projects. They run their LANG for flat stamping plates only because it has a smaller table and only an eight-station tool holder compared to the DATRON, which has a 15-station tool changer and larger table. The DATRON gives them more options in terms of creative engraving, which requires a high level of expertise and flexibility of the machine.

“It is just a very nice machine to work on.  I do a lot of programming for the creative engraving and I am very familiar with the DATRON. My engraving creativity combined with the opportunities a DATRON machine offers is a good melding and these different factors coming together make a product that comes out quick, clean and reliable.” Prohaske says.

Prohaske prefers using a lot of tools. He uses specific tools with angles, shapes and cuts for engraving that help him to create a die quicker. This versatility helps him to achieve engraving effects he wouldn’t be able to produce if he didn’t have so many tools at his disposal on the machine. He has the engraving expertise to know how to apply the right tools for particular engraving challenges. Creative engraving is part of the front end program process where he programs everything and applies it to run on a DATRON.

 “We really try to maintain a good customer service and engraving expertise – the knowledge of what’s gonna work.  For certain types of engraving you need to know what’s gonna work to get an effect. That’s what people appreciate because they don’t know what to do. They come to me and say what’s gonna make this look like what our customer wants. That’s when you build a good report where they can account on you. You are able to do something that other engravers can’t do. That is you edge! I never want to be known as the cheapest engraver … instead, I want to be known as the place to go when something is difficult. And the reliability of DATRON machines and the fact that I’m familiar with these machines allows me to provide this kind of cutting-edge solution.” – Prohaske says.

Download the DATRON Engraving Machine Brochure:

DATRON’s M8Cube the Next Generation High-Speed CNC Machining System

DATRON M8Cube high speed CNC milling machine.

DATRON M8 versus DATRON M8Cube

DATRON M8 vs the next-generation M8Cube high speed milling machine
DATRON M8 and the Next Generation M8Cube High Speed Milling Machine.

For over 10 years, DATRON has had a very successful history with installations of their M8 gantry-style machining systems. This revolutionary machine had an install base of nearly 1,000 machines and was responsible for making DATRON an industry leader in high-speed machining systems. DATRON’s talented research and development team in Germany, in close cooperation with their install base of M8 customers developed a comprehensive wish list for the next generation of machines. In autumn of 2012, the introduction of the new M8Cube answered all the hard work of these collaborated efforts.

When the machine was first introduced to me in the summer of 2012, Matthias Reck, Director of Research and Development at DATRON AG told me, “We were successful at developing a machine with half as many parts, improved ergonomics, better accuracy, faster rapids and feed rates and that’s structurally stronger than the prior M8 model”. The main reasons for this achievement was changing to a new control system and using direct drive AC brushless motors. Additionally, the gantry was completely redesigned with a stronger Z Axis to secure larger horsepower, high-frequency spindles while providing more stiffness for the higher power drive motors. This achieved greater acceleration and deceleration rates producing faster cycle times. The stronger design along with the new control software allowed them to also develop an optimization filter they call “PerfectCut”. This optional software function creates a powerful look-ahead combined with sophisticated algorithm calculations that can improve three- dimensional contour machining by as much as 30% compared to the previous control software. In some sample parts, cycle times were cut almost in half compared to the already impressive M8 cycle times.

Winner of the Red Dot award in 2013, this revolutionary new design not only had a new improved appearance but as well, an easier user interface for the operator. Improvements such as an elongated touch sensitive LCD panel for improved interaction and readability. Additionally, a chip-proof keypad located directly below the display offers better reliability and functionality. A more rugged and self-contained door, hinges upward without having the operator stepping backwards, like found on previous models. The cabin interior has more light to better see your work pieces. An integrated, three-color LED indirect lighting system for indicating machine status is built directly into the gantry that replaces the need for an external light stick. Vacuum ports molded directly into the polymeric table allow for quick and easy installation of modular vacuum tables. With thanks to our customers and design team, the new M8Cube is a much improved machine to use and operate.

The stronger, faster and more accurate M8Cube now has opened up many new applications that were not as attainable with the older M8 Model. Having the possibility for a heavier spindle and larger tool capacity with HSK tooling are two important factors for a broader market appeal. New applications in three-dimensional molds such as thermoforming, heavier and deeper machining operations found in electronic housings and tighter accuracies required in applications such as waveguides are a few examples that make the M8Cube a much more diverse solution in general machining facilities or job shops. Many existing M8 customers have added or replaced their older machines with the new M8Cube for the increased capabilities but more importantly, to reduce manufacturing costs from the faster cycle times and improved ease of use.

For me personally, I am very proud to be working with an organization that has such a strong commitment to research and development. This is the main reason why DATRON AG has been voted a “Top 100 Company” in Germany for innovation. An honor and recognition for this size of manufacturer in a leading country of machine tool producers is truly remarkable. The involvement of the existing M8 customer base along with the talented team of designers and engineers at DATRON have succeeded in making this next generation machine tool, the M8Cube, a monumental successor.

Bill King
President of Datron Dynamics

Download the M8Cube Brochure: