Cyber Week Sale on DATRON Tools! Use Code CYBER22 For 15% Off

CNC Milling Laminated Shims

Milling laminated shims from stock like this laminated stainless steel can present some challenges.

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.

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 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 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.

Recommended Products

Prototype intricate metal parts and small production runs in-house with the CNC system that fits through a standard doorway. Designed for precision prototyping in metal and perfect for a lab environment.
520 x 420 x 220 mm (20 “ x 16.5 “ x 9 “) (XYZ)
40,000 RPM machining spindle
approx. 700 kg (1,543 lbs.)
What if you could shorten your entire workflow with quick programming and setup for faster machining? Remove degreasing and deburring from the equation, and you’re really saving time. It’s not a pipe dream – it’s the M8Cube.
1,020 x 830 x 245 mm (40” x 33” x 10″) (X, Y, Z)
Up to 60,000 RPM machining spindle
approx. 1,300 kg (2,866 lbs.)
In a world where adaptability and floor space are equally important, you shouldn’t have to choose one or the other. Ideal for milling long aluminum extrusions, sheet material, large parts or machine nested small parts.
1,520 x 1.150 x 245 mm (60” x 45” x 10″) (X, Y, Z)
Up to 60,000 RPM machining spindle
approx. 2,500 kg (5,512 lbs.)

DATRON Dynamics Is Your DATRON Partner in North America

Our DATRON experts help many customers bring manufacturing in-house. Reach out to our team to see which machine and accessories are the right fit for your parts.