Caterpillar eyes 3D printing for production parts

  • 04-Apr-2016 03:16 EDT
Brittany Hancock_Cat_additive lab.jpg

One function of the Additive Manufacturing group is to educate Caterpillar engineers around the world about 3D printing and its possibilities, said AM engineer Brittany Hancock.

This past November Caterpillar opened its new Additive Manufacturing (AM) Factory at its Tech Center in Mossville, IL, to consolidate and expand its 3D printing activities and to better serve its internal and external customers by advancing the “disruptive” technology. The AM Factory currently houses many state-of-the-art machines, with plans to expand. These span the gamut of technologies including DMLS (direct metal laser sintering), SLS (selective laser sintering), FDM (fused deposition modeling), SLA (stereo lithography), and material jetting technology. Additionally, located off-site but nearby at the company’s foundry is a binderjet sand printer. Twelve people work in the Additive Manufacturing group, including engineer Brittany Hancock. She recently gave select media, including Off-Highway Engineering, a tour of the new Mossville facility and discussed Caterpillar’s current and future plans regarding the use of 3D printing technology.

Where was Caterpillar’s 3D printing done before this new facility?

There were a couple of machines (SLA and FDM) at the Tech Center in the Rapid Prototyping Lab. In the other building across the street were a FDM and material jetting machine. Last November when the new space was completed here at the Tech Center, everything was combined and some new machines added.

SLA machines are the original rapid prototyping technology, invented in the late ’80s. Cat has used this technology since the early ’90s. We’ve used rapid prototyping for years to produce prototypes, fit-up parts, and scale models. Now we’re investigating the possibility of using additive for production parts.

What are some things you’re currently working on here?

Currently on the machines, there are parts for a new cab interior for a fit-up build at our proving grounds. The engineers want to get a feel for the operator environment. There also are some scale models and various parts for a new concept one of our design engineers is working on.

What’s the advantage of doing it this way vs. a build at a machine shop?

Quicker, and sometimes cheaper, especially if you need one part. Also with 3D printing you can print designs that are not possible any other way. These are the exciting projects and Cat is working on a couple. The interior cab parts we are currently printing are a good example. These are 3 ft long and about 6 inches wide, and to make both of them is going to take about 75 to 80 hours. This may seem like a long time, however the correct material was in the machine, the schedule opened up, and we were able to print quicker than determining how to machine the part out of stock material.

Another good example of the advantage of 3D printing is the track links we printed last year for the manufacturing factory. Cat had a new design about a year ago and the casting wasn’t going to be in for about 10 weeks. In the meantime, the factory had programming for machining processes, measuring equipment, and finishing operations that needed to be completed for the track link. The AM Factory printed 36 plastic track links for them and the manufacturing engineers were able to complete this work before the first cast track link ever came into the factory. Printing saved us time, money, and enabled them to troubleshoot the programs.

Beyond prototyping, do you have any production parts yet?

Yes, some of the parts we have for production are back-up rings, which keep a seal in place on a hydraulic cylinder, and a dealer service tool for O-ring installation. These parts are available through our parts-ordering system and printed on demand.

Another part we have printed for a customer is a shade bracket for an excavator. The shade brackets are generally injection-molded. However, the supplier for the brackets had shut down and the tool was gone. The customer needed one set; therefore, the AM Factory printed the set.

Cat is in the process of looking at other parts for production and completing validation work. When choosing a part for production, you want to make a smart choice and determine that you’ve picked out the right part for the right reasons.

What types of other parts are you looking at for production?

Since they’re not validated yet, I can’t say which ones.

What types of materials do you work with in this lab?

There are plastic and metal materials. The SLA and material jetting technologies print UV-cure plastics. The FDM printers print plastic grades that are generally used for injection-molded plastics—ABS, nylon, ULTEM polyetherimide (PEI) [from SABIC], polycarbonate, and ASA (acrylonitrile styrene acrylate).

Currently our metal printer is running 17-4 stainless steel. Once we are good at printing this material we will try another material. Metal printers have the ability to run aluminum, stainless steel, maraging steel, and cobalt-chrome. This machine was a new addition and just came online earlier this year.

What determines if you use metal or plastic for a part?

The end use of the part determines material type. If a design engineer has an NPI (New Part Introduction) part that they are looking for a mockup of or a simple fit-up part to see how it interacts with other parts, generally we recommend printing that type of part from plastic. Even some production parts we’ll make out of plastic, because that is what the design requires. It’s about getting the right material for the job and that’s part of our job here at the AM Factory. People come to our Additive engineers with what they want and the knowledge of what the end use for the part will be, then we help them determine what printing process, material, and post processing is needed to get the right part for the job.

What are some parts that you would agree metal is best for?

Parts that are going to be exposed to higher temperatures or chemicals that the current plastics for printing cannot withstand or parts with high structural loads. For example, prototype engine parts like rocker arm and fuel swirlers could be direct metal printed.

Low volume or prototype castings are also good candidates for printing because the mold can be printed from a sand printer then the part poured from production-intent metal. This provides a good way to get a metal part without printing the part, but the tooling to produce the part.

How busy are you? How long would I have to wait if I have a request?

Currently the AM Factory is fairly busy. There is a schedule for all our printers. We generally tell people two weeks from the time they approve the quote to have a part in hand. Variables that effect the timing are: what material is being requested and when is that material scheduled to run in the printer, what type of finish is required, are the files provided ready to be printed or is there pre-work involved to prep the files for printing (there is almost always pre-work required), and what post work is needed (paint, sealing, machining, etc.).

What is Caterpillar doing to expand 3D printing organization-wide?

Another thing the AM group is trying to do is educate engineers about 3D printing. With locations all over the world and thousands of engineers, that can be a difficult task. One program that has worked well for us is the Nomadic Printer Program. This program loans a small FDM printer to a group for about 6 months. This gets engineers and others outside the AM group exposure to 3D printing. This program has been in place for about a year and a half with a very successful outcome. Our manufacturing facilities have used these “nomadic printers” to create customized tooling for their facilities that saves them time, money, and makes their job safer.

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