Meeting tight tolerances

Ipswich, Massachusetts-based Advanced Precision Engineering Inc. (APE) is a leading supplier of complex machined parts, assemblies, and kits to the medical, aerospace, military, automation, and semiconductor industries. When APE landed a project for a housing that goes into medical diagnostics equipment, they went looking for a machining center that could handle the serious amount of hogging-out required.

The search for the right machine

“We have 37 high speed machining centers, and in the past everything we’d done was satisfied by our existing 5-axis machines, which all feature vertical spindles,” says Alan Soucy, president & CEO.

But the new medical housing part was different. Starting with 165 lb of material, the end part weighs just 36 lb, and this tremendous amount of hogging-out can cause issues with chip evacuation.

They began looking for a machine with a horizontal spindle, allowing them to flip the part 180º in the work environment, making it easier for the chips to fall and be removed by the chip conveyor.

Soucy thought if they were going to use a new horizontal 5-axis machine, they wanted to do it right. They began by reviewing their existing stable of machines and discussing what brands they might be comfortable with. Their other high speed machining centers use Heidenhain CNC controls, which Soucy calls the gold standard for 5-axis machines, light years ahead of other options in terms of ease of use. Because APE likes to lock in when they choose a control for a particular machine type, they focused the search on horizontal 5-axis machines using Heidenhain controls. “We needed multiple operators and engineers to be trained on the controls so anyone could operate any of the 5-axis machines.”

That search culminated in the selection of a G350 5-axis universal machining center (UMC) manufactured by Grob Systems. The G350 features three linear and two rotary axes, giving operators 5-axis simultaneous machining and interpolation. The axis arrangement facilitates upside down machining, and the horizontal spindle position ensures the longest possible Z-travel path and optimum chip fall.

Manufacturing facility reflects reliability

Soucy originally saw the machine at the International Manufacturing Technology Show (IMTS). Four years ago, he traveled to Grob’s Bluffton, Ohio, manufacturing facility, two years before they bought the machine.

“I needed to see the machines in person, so I flew there and toured the facility, which blew me away,” Soucy extolls. “The way they operate and how they train apprentices is inspiring. They show how each apprentice starts out in the company and how they move along, so they know everything about the machines they’re building. It’s an impressive facility and I had an aha moment – I knew I would buy one when the right job came up.”

Soucy is also gratified that their machine is one of the first ever made in the U.S. to use the Heidenhain controls.

In addition to being impressed with the factory, Soucy also reasoned that Grob’s long and successful history of work in the auto industry translates into serious reliability. Reliability was the main reason they were looking for Grob equipment.

Soucy also has nothing but praise for the machine installation. “It came on a truck, and everything was in one unit including the chip conveyor. The only thing not fully assembled was the chiller unit. Usually, a machine has a ton of options, each arriving separately. With our machine, one fork truck picked up the whole machine and the only thing left to connect was the chiller. Then we had 2 weeks of validating and commissioning the machine. The people they sent were spot-on knowledgeable.”

Soucy notes several people tried to dissuade him from purchasing the G350, saying the welded frame isn’t as robust as cast iron and would result in too much vibration. During the factory tour, Soucy gained confidence in how the machine is built. He says, “I asked myself, ‘Is there any truth to the problem with welded frame construction?’” He found none. “There’s no vibration – all you are hearing is that smooth, sweet cutting sound.”

Another positive feature is Grob’s ability to log in remotely to tune the machines. For example, the housing’s weight on the table offsets so dramatically that sometimes when the rotary and tilt want to move at high velocity, it gives feedback. In that case, Grob logs in and tunes the machine in 30 minutes.

Because the G350 uses the same Heidenhain controls as its other 5-axis machines, the company could hit the ground running without much training. Before they purchased the G350, machining took six operations for this part. The new machine took it down to two operations plus an off-line dovetail prep-operation to hold the part. It was done on a horizontal 4-axis machine but with the 5-axis, instead of having to flip the part and re-fixture, they can hold the part on the dovetail and rough out the part, then finish without removing it because they’re able to hit five sides of the part at once.

Behind the hood

The G350 has a unique arrangement of the three linear axes, which minimizes the distance between the guides and the machining point, lending the machine considerable stability. The full tool length can be employed in any axis position, even with maximum part size. Even with extremely long tools, operators can swivel and machine the largest possible component within the work area without collision.

With a swivel range of 230º in the A-axis and 360º in the B-axis, the G350 offers the greatest possible positioning flexibility. The G350 also features absolute position encoders, an air purge seal in all linear and rotary axes, and a disk-type tool magazine for fast tool change. The central, ergonomic arrangement of the machine components guarantees optimal accessibility to the fluid cabinet and electrical cabinet, as well as easy access for preventive maintenance and inspection.

Savings, impressive accuracy

With a goal of integrating four machines into a 100-palletized system with a pallet changer running seven days a week, APE began with one single machine to make sure it would perform as envisioned. The company plans to add 20,000ft² to its existing facility and the machine will be placed there. In addition to running the new medical housing job, the G350 will be used for a critical housing in the missile/defense industry. Other plans for the G350 include handling new business and taking some jobs that are currently running elsewhere and automating them.

According to Soucy, the spindle reliability is impressive, providing great accuracy. “The medical device housing we’re using the machine for has a lot of tight tolerances and the only change we see is due to tool wear. The machine is spot on, as accurate as our other 5-axis machines, and it meets our very high bar.”

Advanced Precision Engineering Inc. (APE)
https://www.ape10.com

Grob Systems Inc.
https://www.grobgroup.com
IMTS 2022 Booth #431400

Heidenhain
https://www.heidenhain.com
IMTS 2022 Booth #135716 / #215600