Here is an aluminum part used in a production line to make gloves. The programming and machining are straightforward except for the curved track that wraps around the tip of the part and required milling in two setups using small cutters. The parts are about 4″ long.
This five part assembly is machined from 303 stainless steel and is about 4″ across the widest span. The main part is hollow with a wall thickness of just under 0.100″. Two days were needed to program and cut these parts.
The part is about 7″ by 10″ and approximately 3″ thick. It was a challenge to machine because the wall is only 0.200″ thick and required special measures to keep vibration and distortion under control. Over 30 programs were needed to run the part and the total runtime and programming time was almost 40 hours. The material is Alumec 89 aluminum. The raw block weighed almost 25 lb (11.5 kg) and the finished part is 14 oz (390g).
1. TOP VIEW: The part has been milled, handworked and fine glass beaded. The logo was milled using 1/32″ diameter cutters and stands about 0.150″ tall. It is proud of the surface by about 0.025″
2. TOP VIEW #2: A view from the other end
3. UNDERSIDE VIEW: This side was milled first.
4. HALF MACHINED IN THE MILL: This part is being milled in my Haas Minimill. The underside is already finished and the first 2″ of the top is roughed. The red stuff peeking out at the corners is Plasticene used to dampen the vibration as the part is milled. The Plasticene and milling strategy of cutting it in 2″ sections was the only way to keep the part from self destructing during cutting. Blending of successive sections was done by dropping the cutter in small increments until the new cuts just kissed the previously milled surface.
New Wire EDM Capability: Here is a good example of what the rotary axis can do.This nitinol pin is used to hold a dental implant onto a special wrench during implant surgery. The material is very hard and also super elastic making it very difficult to machine conventionally. This tiny part was burned in one setup on the wire EDM to tolerances of +/- 0.0002” using the rotary axis in indexing mode.
Another tiny part cut with the rotary axis. Parts like these are still expensive to cut using such a slow machining process but there is really no other way to make something like this. By the way, the little vanes are 0.015″ thick and 0.020″ wide. They will be laser welded onto a 1/16″ diameter tube, then cut free from the stub at the bottom of the picture. If you look closely, you can see a tiny notch cut into each vane…that’s where I’ll make my cut under the microscope with a diamond disc.
Shown is an experimental surgical bur used by a scientist for bone surgeries on rodents. It was one of several attempts to find the best geometry for the cutting tip. The tip is 1.8 mm diameter and has three cutting flutes. It is made from 440C surgical stainless steel. The tip geometry is created by rotating the rotary axis 180 degrees synchronously as the wire follows a curved path 4 mm long. The shank is 0.8 mm diameter and is left rough since there was no need to incur the expense to wire it to a fine finish. Overall the part is 25 mm long.
This is an injection mold for a rubber part. On the right, the cavity has been EDM machined to a coarse finish to give the part a matte texture. The left side of the mold and most of the right side was milled with CNC.
Shown are a couple of electrodes used to EDM a mold cavity. These are machined from copper or graphite and are consumed in the EDM process. The wear on the corners of the blackened electrode on the right is normal for the process; a second or even third electrode must be made and used up to finish the part to correct geometry.Each electrode is time consuming to make and set up in the machine. The process is also intrinsically slow, these electrodes are about 2 inches long and are burned into a hardened steel block about 3/8 inch deep. Each burn took several days to complete and required 3 electrodes to get the detail and finish required in the part.
This is a 32 microinch finish; about as fine as can be produced in a reasonable amount of time.This tiny gear required about an hour on the machine; making the finish significantly better would require another electrode and many hours of additional burning. Extremely fine finishes are very time consuming and expensive to obtain.
The largest outside diameter is 3/16” (just under 5mm). The weld is about 0.02” wide (½ mm). You can see my grubby finger under the assembly for a sense of scale. The material is 17-4 PH stainless steel, welded to nickel plated 304 stainless steel tubing.
The gear is 0.25″ diameter (6.25mm).
The material is 17-4 PH stainless steel.
The cores have worn in the corners and are flashing during molding. The repair must not gouge the corners of the existing part, and must be built up enough for refinishing. The material is P20 mold steel.
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