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Micro Machine Shop

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Machining Company Produces Small, Complex Parts for Medical and other Industries

Small Medical Parts

Micro Machine Shop's Mike Resz discusses the company's work with demanding, tight-tolerance parts

Although it turns out parts for various high-end industries, including semiconductor equipment, microwave, and valve applications, Micro Machine Shop has worked its way onto the radar screens of medical device companies for its ability to produce precision machined parts, including those with close tolerances and complex configurations. The Oakdale, Calif., company, which operated out of Silicon Valley for many years before recently re-locating to the San Joaquin Valley, offers a formidable one-two punch of precision CNC milling, turning, and Swiss screw machining processes along with secondary finishing techniques to deliver the polished aesthetics so often coveted by makers of medical products.

As its name suggests, Micro Machine Shop (www.machining.us.com) specializes in miniature parts, many of them tiny, but is capable of machining medium- and larger-sized parts as well. The company has a leg up on many others due to its ability to machine parts in a wide variety of materials, spanning metals and plastics, and for its readiness to take on prototypes, short runs, and production quantities.

Design2Part Magazine's David Gaines caught up recently with Micro Machine Shop President and owner Mike Resz. On a sunny, sweltering afternoon typical of summers in the San Joaquin Valley, Mike shed some light on how his company has earned its stripes as a respected supplier of parts for demanding industries, including medical and semiconductor equipment. Following is an edited transcript of their conversation.

D2P: Why is Micro Machine Shop a preferred source for medical parts manufacturing?

MR: We're a preferred source for medical parts mainly because we know how to make small parts--parts that are close tolerance--and we use many different materials. We often use titanium and plastics for medical parts. We also use the 300 series of stainless steel, and high-tech plastics like Delrin® and PEEK®. I also think we're in demand for medical parts because we can use a variety of hard-to-work-with materials, especially for the plastics. Many machine shops won't work with plastics at all because they don't have the expertise to process them.

D2P: What gives your company the expertise to work with the plastics?

MR: I've been in machining for 35 years, and a lot of my machinists have been in this business for a long time, too, so we have a large body of expertise to draw from. With the plastics, there is always a possibility of the parts deforming from heat. You can think you have a part right, but if you look at the part under a microscope, you might find a minute piece of the plastic that has melted. So you always have to make sure your feeds and speeds are correct, that cutting tools are sharp, and we also do a lot of testing and quality control after the parts are made. Almost all of these parts have to be checked with a microscope. These medical parts have very critical uses, so we deal with them very carefully.

D2P: Can you give us an example of a type of part or component that you produced for a medical application?

MR: We've made surgical tools for doctors and dentists. They are mainly manual tools, like miniature hex drives for hex nuts and bolts. The parts are very miniature and very long.

D2P: Were there a lot of critical finishing processes for these tools?

MR: Yes, they had to be burr-free, perfectly straight, and perfectly smooth. There are a lot of considerations when we make these medical parts.

D2P: What are some of the major design objectives with these products?

MR: The finishes are always critical. The aesthetics are also important; they have to look really nice. We always put a polished finish on them. We achieve the best finish we can with the machining, and usually a secondary de-burring and hand polishing process. We do the hand polishing on a small conventional lathe with emery cloth and polishing compound.

D2P: What are some of the technical challenges of producing parts for medical devices or equipment?

MR: There are challenges with the titanium parts. Your machining processes have to go just the right way. Many of them are done on the Swiss screw machine. Titanium is on the soft side, so the parts may bend on you, making it difficult to machine. The implant screws are done on the Swiss screw machines with titanium. I think that most of the implant parts are either titanium or stainless steel, which we also work with. There are a lot of screws that we make for the implants, and implant parts are one of our specialties.

D2P: Are there any other technical challenges in doing the titanium parts?

MR: Most of them have to be machined so that they are burr-free right off of the machine. We have to make sure that the tools are sharp, and the feeds and speeds are correct. If there are microscopic burrs on them, we will tumble them.

D2P: How are you able to meet the manufacturing requirements for medical parts?

MR: In most cases, the customers don't want fast turnarounds because they understand the critical nature of the parts--it's not something that you want to rush out the door. The requirements for these medical parts are stringent, so the inspection process is very important. Most of these parts are viewed under a microscope for the burrs and finishes. They are mechanically measured and also inspected under an optical comparator. So there's a great deal of quality control that goes into these parts.

D2P: What types of medical products seem to be in most demand these days?

MR: We're seeing a lot of surgical and dental tool parts these days. We also make parts for medical devices and equipment, which are usually special stainless steel screws. Many of these parts are made on our Swiss screw machines. The general job shops usually don't use Swiss screw machines, so this kind of sets us apart, too. We'll also do the low volumes, since the large shops will only do the large volume jobs. The low-volume quantities are something we specialize in, especially for the screw machine parts. We might make 50 parts for a company that will last for six months.

D2P: You also handle prototypes. Can you explain your prototype work?

MR: Yes, we also make prototypes for the medical industry. Most of them are so small and intricate that they have to be done on the Swiss screw machines. We can usually rush a prototype through the shop in two weeks, from beginning to end.

D2P: Do you have any engineers on staff, or do you wear that hat, too?

MR: I'm also the staff engineer, so I check all of the prints when they come in for a new job. And if they're open to it, I can give them design and engineering assistance.

D2P: Can you give us an example of one of the miniature or micro parts that you made?

MR: One part was an electrical contact that was about one inch long. It started at 0.001 inch at the tip and tapered back to 0.0010 inch.

D2P: What's the difference between a micro part and a miniature part?

MR: I don't know exactly where it would start and stop, but a micro part is smaller than a miniature part. In terms of size, some of our smaller parts would qualify as micro parts. If it's a hole drilling application, we'll go down to about 0.010 inch.

D2P: You also machine in micro features--such as holes, slots, and notches--on your larger parts. Can you tell us a little bit about the micro feature work?

MR: [Machining micro features] is also a specialty of our company. On larger parts, we might be tapping a part that might have 0-80 or 000-90 thread sizes. We can do the miniature drilling and tapping. I don't think a lot of machine shops are doing this type of work either because I get a lot of calls for it.

D2P: What is it about the equipment and process capabilities that you have that enables you to do this type of work?

MR: The main reason we can do this type of work is because of our setups and the type of tools that we use. Setting up the tools correctly in the holders is important--for example, putting a drill tool in the holder the right way so that there's no run out. Also, having the best tool holders is necessary.

D2P: It looks like Micro Machine Shop can also provide large parts, in addition to the small parts. Is that correct?

MR: Yes, we do. On milling, we can go up to a part that is 20 inches by 40 inches. On turning, we can go up to a 12-inch diameter part; so we have a wide variety of sizes that we can do for the OEMs. I tell them that we're a one-stop-shop--we can do the smallest and largest parts, and we can also handle low- and high-volume production runs. On milling, our average size is about 100 parts. For screw machine work, we do work from 10 parts to 100,000 parts, and regular turning is about 100 parts. I think that a lot of machine shops don't want to do the short runs because I don't think they want to take the extra time for a low volume.

D2P: Your company also does semiconductor and microwave parts and components. Can you describe some of these parts?

MR: These parts are mostly for semiconductor machinery. The semiconductor parts are usually general types of machining, from milling to turning, and big to small sizes. One application has them going into high-temperature ovens, which are usually 316 or 304 stainless steel. And they do have special considerations because of the high heat that they are exposed to. We have to machine the 316 material at lower rpms and feed rates.

The microwave parts can be miniature housings for miniature electrical components that are often about one inch square. A lot of them are filters or amplifier housings. Some of the larger ones go up to about 7 inches x 12 inches and are three inches thick. We also have to machine a heat sink into this part. These parts can have hundreds of complex features on them.

We also make input and output fittings on the CNC lathes for the microwave industry. These are used to hook up the electrical devices to the housings. They might be used to hook up an antenna to a radio, and they have a lot of military applications. Some of these microwave parts are also used in the aerospace industry; some of them go up in missiles. All of these are complex, tight tolerance, precision parts.

This technical information has been contributed by
Micro Machine Shop

Click on Company Name for a Detailed Profile

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