Design News for Mechanical and Design Engineers

Tony Pelke, senior process engineering manager, Phillips Metal Injection Molding facility: Since about June of 1996, and I have been involved in some way with every program that has come through this facility, which totals about 350 different parts. Over the years, we’ve developed more than 300 tools for metal-injection molding prototype and production programs.

DN: What kinds of resources do you have at your Menomonie MIM facility?

TP: We have seven Arburg injection-molding machines at this 35,000-square-foot facility, which was built specifically for metal injection molding in 1998. They range from 18 to 80 tons of clamping force. They are all equipped with robots, which remove the injection-molded parts and place them on fixtures for the debind and sintering processes. We also have two batch debind ovens, which typically are used for larger parts and specialty alloys, such as commercially pure titanium. In addition, we have two batch furnaces. So if we use the batch debind process, we do the final sintering in the batch furnaces. Beyond that, we have a continuous debind, continuous sintering operation for high-volume jobs. We can stack parts anywhere from one to as many as six layers high to increase the throughput. We can also do some light machining if a part needs simple finishing work. More elaborate finishing work, such as heat treatment and application of special coatings, is done by outside contractors.

DN: Any plans for new equipment?

TP: We have plans for another continuous sintering, continuous debind operation, with equipment scheduled for delivery in December 2007. So we should be up and running with that furnace during January of 2008. This $2.5 million investment will almost immediately double our capacity, which we need because we are growing very rapidly in metal injection molding.

DN: What’s the typical lead time for production of a MIM part?

TP: It depends on the complexity of the part, the alloy used and the number of secondary operations. In general terms, it takes from four to eight weeks to build a production tool for a new part. Most jobs fall in the 10- to 12-week range.

DN: How many different alloys can you work with?

TP: Working with BASF feedstock, we offer quite a selection. We routinely run 10 to 15 different alloys. And we can always work directly with BASF to address special needs of customers.

DN: What are the factors that point to MIM being a good alternative for a part?

TP: Basically, MIM works best with small, complex parts with intricate geometry. Think about products that might fit into the sphere of a golf ball, or a tennis ball at the largest. You also need relatively high volume –10,000 pieces and up -- to justify the tooling expense. We’ve run many volumes in the range of 100,000 to 250,000, and one automotive application totaled 5 million units. We are now ramping up for another auto application that will run 7.5 million pieces, and we’ve had projects involving cellular phone assemblies that have run to more than 4 million pieces.

DN: Is structural strength another indicator for MIM?

TP: Oh, yes. If plastic is sufficient for a part, make it in plastic. It will be considerably cheaper. The main competitor for MIM is investment casting and machining.

DN: How can customers make the most of Phillips’ metal injection molding know-how?

TP: Contact us as early as possible in the design process, so that we can optimize the parts for metal injection molding. We want to minimize the tight tolerances, develop a flat setting surface, and eliminate secondary machining as much as possible. So let us critique the part so that we can do the best job of producing a quality part efficiently and cost effectively.

DN: Do you also give advice on the type of alloy to be used?

TP: Our metallurgists can provide recommendations, but most customers do have particular alloys in mind. 

DN: What are the most dominant applications that you are seeing for MIM?

TP: Right now, we see a lot of medical applications, such as surgical jaws, clamps and other surgical instruments. We probably have some 20 different surgical jaws that we produce from this facility. These are typically made of 17-4 stainless steel. In total production of MIM parts, automotive continues to lead, with clutch components, fuel injector components, turbo charger parts and other applications. The firearms market also is very significant, with such components as triggers, sights and the like.

DN: In general, what is driving the growth that has led to such an expansion of MIM facilities at Phillips?

TP: Much of it can be traced to customer confidence, based on the many projects that we’ve handled. We really have established ourselves as one of the leaders in the industry. Our policy is to be honest and upfront with customer about what we can do. We don’t over commit, for example, to achieving a tolerance that we know we can’t hit.

	This graph of NovaTorque's IEC 55 motor shows efficiency versus torque and speed.