Established in 1990, Poole, Dorset-based subcontract machining company, Aerotech Precision Manufacturing specialises in the CNC turning and milling manufacture of precision parts in low quantities.
For the past eight years, the company’s programmers have been using Mastercam supplied by CNC Software, Inc. CAD/CAM software with the Solidworks plug-in feature. Most of the company’s manufacturing processes include CNC milling and turning. The software has kept pace with designers as they have developed increasingly complex parts.
“The designs have such intricate shapes, it’s really not possible to program them by hand,” begins Andy Harvey, Aerotech operations director. “We need the ability of the CAM software to transform the data for the model, which can have all sorts of fancy shapes and profiles. The software will then turn that into machine code. It’s a tool that we can’t be without because the ergonomic shapes of the designs we have to come up with really preclude the ability to manually write the code needed to produce these shapes. Machines just follow numbers. It’s quite simple, but taking those numbers from a design is quite complicated.”
Customer designs arrive at Aerotech as electronic models and step files, which provide an onscreen visual of each product. Designers use 3D modelling software to choose finishes, part configurations, and design parameters. The part is divided into individual component parts and a model is created. The step files are then used to create the CNC program that drives the machine tool. Mastercam’s Dynamic Motion technology permits higher speed rates and smaller depths of cut and finishes. Algorithms programmed within the software intelligently detect changes in the material based on the toolpath, so the cutting tool remains engaged with the material. The result? Reduced cycle times, less tool breakage, and reduced machine wear and tear. Solid-model cut verification and machine simulation via the software’s Verify function ensure cutting accuracy.
“You can prove it all out electronically,” states Aaron Houston, business development manager. “You can see the toolpaths, you can see where the tool is going. The graphics are very sophisticated. The machines have safety built into them so you know you’re not going to plough your head into some fixture ring or something like that. You can effectively see the tool do its job first, before you actually get anywhere near the cut metal.”
Aerotech offers customers the option of eliminating the casting process. When compared to casting, machining from solid results in a better-finished product and shorter lead-times. For example, a customer contracted the company to manufacture cast aluminium alloy boxes. Stress analysis revealed that, after a period of time, the boxes were highly stressed and cracking. To avoid these pitfalls, designers created the part from a solid fabrication. CNC operators machined components together and produced parts more quickly and cost effectively compared to the casting process.
“The advent of this software enables the designers to design more complicated shapes which would have been cast and then lightly machined,” adds Houston. “Now we can avoid the time scale to create castings and the inherent problems and costs with that. It’s a much more efficient way of getting from A to B. Lead-times are a factor as well. We’ve been able to reduce the lead-times on these complex parts for the customers’ benefit. Mastercam allows us to create shapes that historically would have required casting, forging of some kind of push-form billet shape.”
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In another application, the team put its CAD/CAM software to the test when programmers created a complex product for the airline industry. An international commercial airline contracted the manufacturer to create three barstools for each first-class section of the upper bar area on 12 airliners. The contemporary shape of the barstool was a challenge. Manufactured from a solid billet of L93 aluminium, the barstools were roughed and finished on a multi-axis bed mill.
“It’s going back to the question of complexity,” Houston continues. “With the barstools, there was an application challenge and we resolved it. They were machined out of a solid billet of aluminium. The product was extremely complex in terms of shape and surface finish.”
To rough the shape of the airliner barstools, the programmers created high speed toolpaths that removed the material rapidly, with minimal air cuts. The tool’s ability to stay engaged with the aluminium allowed it to smoothly move from one shape to another without cracks or tool breakage. In all, a 500,000-line program was generated.
Speed and efficiency were key throughout the lengthy milling process. Machining the barstools meant removing a significant amount of billet material. The software’s 3D machining, with automatic leftover removal feature, more than proved its worth: the product in the semi-finished state started at 551lbs. and was cut down to a mere 24lbs. The final product dimensions were 980mm x 235mm x 415mm. Additional software features such as easy pocketing, contouring, and drilling made for a smooth machining process. Once the team completed the roughing and initial finishing, the semi-finished barstools were transferred to an outside manufacturer for mirror polishing, gold plating, and leather binding.
To meet current customer requirements and attract new projects, Aerotech purchased a 5-axis universal milling machine with large work envelope and tool magazine. Without the software, Aerotech’s eight CNC programmers would not be able to employ all of the machine’s 5-axis capabilities due to the complicated written programs it requires. The CAD/CAM software is needed to run in tandem with the machine.
The need for speed
According to Harvey, Aerotech does not have the luxury of producing its own product and cannot afford to sit on any incoming job. Quick response time is critical to the success of this contract job shop. 80% of Aerotech’s business comes from returning customers.
“This CAD/CAM software has opened up markets for us that we would not be able to make parts for if we didn’t have access to Mastercam,” Harvey concludes. “It’s as simple as that. We would not be able to sit down and make these, draw these, give the machines the code to work by hand. By nature, we are a reactive company. We don’t get long lead times for what we do. Mastercam helps us shorten lead times by giving us machine codes quicker. We wouldn’t be able to do some of our jobs without it. Everything is getting smaller and faster.”
A few years ago, one customer’s part took nine months to manufacture. Today, the company turns around that same part in nine weeks. It recognises that efficiency and flexibility are the keys to stability and profitability in a high-end-product market. By expediting design and machining processes and tackling complex part geometries, CAD/CAM software will help Aerotech cut its own path to ongoing success.