Moulding the Future

Advanced CAM techniques help Cap-Thin Molds reduce cycle, lead times

Moulds created at Cap-Thin are bench-free because
the company’s machine tools are able to produce
high-precision, high-finish parts.

Moulds created at Cap-Thin are bench-free because the company’s machine tools are able to produce high-precision, high-finish parts.

Cap-Thin Molds, Mississauga, Ont., a manufacturer of precision, multicavity tools for caps and closures, has a unique value proposition. The company guarantees cycle times, and if the tools don’t perform accordingly, it returns the customer’s money.

Carmen Goudey, manager of CNC operations, explained that customers sometimes resist the idea of paying a few thousand dollars more for Cap-Thin’s high-precision tooling, but once the tools start producing, it’s a different story.

A recent 12-cavity tool was guaranteed to deliver an eight-second cycle. The previous mould that was in continuous use for five years had a 12- second cycle. The extra cost of the tool was recovered very quickly.

When cycle time drops, the next problem becomes lead time.

Cap-Thin came into being in 2013 as the result of a merger between two highly regarded toolmakers that wanted to grow their infrastructure to satisfy customer requests for more tooling and shorter lead times. At the time of the merger, lead times for 32-cavity moulds typically were between 18 and 20 weeks.

Today the manufacturing operations are consolidated within a new, larger facility, and lead time for a 32-cavity mould has been reduced to eight to 10 weeks. Goudey said much of this lead time improvement is credited to the company’s use of 4-axis, high-speed machining centres and advanced CAD/CAM software.

Bench-free Machining

Programmer/machinists create CNC programs based on solid models sent from the engineering department.

“We pride ourselves on the fact that our moulds are bench-free. The machine tools are very accurate and our surfaces are extremely high-precision and high-finish. When the components come off the machine, everything fits like a glove. There is no hand work involved,” said Goudey.

Cap-Thin’s programmer/machinists create CNC programs
in Mastercam based on SolidWorks CAD models sent
from the engineering department.

Cap-Thin’s programmer/machinists create CNC programs in Mastercam based on SolidWorks CAD models sent from the engineering department.

The company’s CNC shop typically has 15 to 20 projects going on at any one time. Each machinist programs, sets up, and operates his own machine. Each CNC machine has a computer with its own seat of Mastercam installed on it, and the company has 13 total seats of the software — 10 mill and three lathe.

“We specialize in high-speed machining. The bulk of our equipment are 4-axis, high-speed machining centres,” explained Goudey. “To take full advantage of them, you need specialized software. [When we started using] 3-D, high-speed toolpaths, it was a real game-changer for us. We started out using some of the high-speed toolpaths and some of the legacy. For the most part, now we can do everything we need to do with the high-speed toolpaths.”

To make such intricate, high-precision components, Cap-Thin’s programmer/machinists typically do not rely on the “book value” when setting machining parameters.

“We will program what we think is correct and then the tool talks to you. You can usually hear it and see by the motion of the machine if you are at risk of breaking a tool or having it pull out of the chuck or if there is a problem with evacuation,” said Goudey. “Based on what the tool is telling us, we fine-tune the feeds and speeds to what seems to be most acceptable for that particular part. Then we capture everything in a Mastercam file so that when we have to make the part again, it’s plug and play.”

High-speed machining in combination with reducing the number of setups, tool changes, and secondary operations have all played an important role in reducing lead times by almost 50 per cent in many cases in the shop. However, none of these time-compression strategies are viable if they in any way compromise the machining precision that ultimately contributes to cycle time reduction on the injection moulding press.

Chasing Tenths

“We are chasing tenths. That is a challenge because there are so many factors that go into maintaining accuracy,” said Goudey. “We control temperature in our shop to 1 or 2 degrees Celsius. All of our machines are on special vibration-dampening foundations. Our cooling is tightly controlled because equipment operating at 42,000 and 30,000 RPM will generate a lot of heat and spindle growth.”

The company also just implemented on-machine gauging with spindle probes to eliminate the need to take complex components off the machine for in-process checks at the CMM.

Cap-Thin also is increasingly relying on roughing toolpaths incorporating dynamic motion technology to minimize cutting tool wear. This not only reduces tool costs, but also improves manufacturing process accuracy and consistency.

“With dynamic toolpaths, our tooling costs are lower because we are using multifluted, variable-geometry carbide end mills. We can use the flute of the end mill rather than having toolpaths where you are stepping down in small Z steps and all the wear is distributed on the bottom corners of the tool,” said Goudey. “With dynamic [motion] you are using a deeper depth of cut with a shallow radial depth of cut that distributes the wear over a larger portion of the tool. Our tool life is probably 10 times better, evacuation is excellent, and there is less wear and tear on our machines.”

Looking Forward

Simply building a complex, precision, multicavity tool is not enough to ensure the reduced press cycle value proposition will actually be fulfilled. This is why Cap-Thin has a test facility with three injection moulding machines dedicated to verifying that moulds are production-ready when they arrive at the customer.

Another recent venture to add value is a partnership with a moulding machine builder to develop a system that makes it possible to perform two-colour moulding on a conventional press.

Goudey said that the company also continually updates equipment to improve precision and break bottlenecks. Securing a steady stream of qualified workers who can understand and use these technologies effectively is a concern that is being addressed via work-study programs that Cap-Thin is involved in with two local area colleges.

“All these things involve a lot of work,” he said, “but it is something we owe our loyal customers who are rewarding us with more business.”

Contributing writer Joel Cassola can be reached at joel.cassola@gmail.com.

Cap-Thin Molds, 905-564-7424, www.capthinmolds.com