In the driver’s seat

(from left) Kevin Burton, Sandvik Coromant product manager for turning; Adrian Dabrowski, plant program manager at THK Rhythm Automotive, and John Horsky, Sandvik Coromant account manager discuss how the new GC4415 grade insert has helped the company save 194 hours of production time per year while experiencing far less downtime and more reliable production.

Situation

Tillsonburg has come a long way since country music legend Stompin’ Tom Connors thrust the small Ontario town and its tobacco fields into the spotlight with its namesake song. Today it’s part of a thriving automotive region, and home to a THK Rhythm Automotive plant that serves global manufacturers, including BMW, Ford, and Mercedes-Benz Group AG.

Automotive is a tough, competitive sector, which means THK Rhythm Automotive needs to make its parts stand out from its competitors.

The plant specializes in suspension components, along with ball joints and ball studs for those components. Being a global automotive player demands stringent quality and cost-optimization measures, which is evident in the THK facility.

The company’s quality policy, which is prominently displayed at the plant’s entrance, reads: right the first time, right every time, continually improve.

And it’s more than just a catchy mantra. Several manufacturing improvement practices show this policy at the plant, including kaizen, a Japanese term for continuous improvement, which THK uses to focus on optimizing efficiency, productivity, and overall equipment effectiveness (OEE).

A Challenging Machining Process

Despite THK’s crystal-clear efficiency goals, reaching productivity targets while controlling cost recently was a challenge when producing a front lower tension arm, a component that goes into the suspension assembly of a car.

“The front lower tension arm requires the removal of a lot of material during several steps, including drilling, roughing, and finishing a bore,” explained Adrian Dabrowski, plant program manager at THK Rhythm Automotive.

The component is made of a forged ISO P steel that is particularly abrasive with a high tensile strength. Machining this part requires a special tool with numerous inserts that are staggered—meaning they are not all of the same diameter.

The original machining process for the front lower tension arm was designed to make 140 parts per tool. However, the company found it could only produce about 92 pieces on average before one of the inserts on the largest diameter failed, causing the entire tool to fail.

Frequent failure means operators have to change tools far too often. The machines in the THK Rhythm Automotive workshop are set up in a way that, if one tool breaks, a spare tool is brought in automatically so that machines can keep running. With frequent tool failures, however, there were not enough spare tools to keep production flowing.

While GC4425 delivers improved wear resistance, heat resistance and toughness, GC4415 is used when better heat resistance is needed.

Chip control, a vital consideration for any steel turning operation, also was a concern.

“When the tool failed, chips would often get wrapped around it, so we had to physically take the tool out and remove the chips,” said Gary Martin, a machine operator at THK. “These chips were sharp and could cause finger cuts and injuries.”

Dabrowski further highlighted the pains of tool failure.

“We were running the machines with just a single tool, and when that tool broke, the operators had to physically take it out, manually change all the inserts, and put it back in the machine. That equates to around five to six minutes of downtime per machine, which quickly adds up,” he said.

On average, operators oversee three machines. So, if one machine is down, in essence all three are down.

“On good days, we had just one breakage per shift,” said Dabrowski. “Even on these good days, downtimes were as frequent as three to four times per shift per machine.”

Using these inserts created a lot of downtime, which made meeting daily productivity targets difficult.

To give its products an edge, the company enlisted the support of Sandvik Coromant and its new steel turning grades.

Resolution

In search of the right option, the company tried to adjust the machines daily, fine-tuning feed rates and RPM. The team also tried different inserts and geometries but nothing hit the mark.

Sandvik Coromant added two carbide insert grades, GC4415 and GC4425, to its existing range at the end of 2020. These inserts have a broad range of applications and are recommended for both continuous and interrupted cuts. While GC4425 delivers improved wear resistance, heat resistance, and toughness, GC4415 complements GC4425 where enhanced performance and better heat resistance is needed. For THK Rhythm, GC4415 was a fitting addition to its machining process.

For THK Rhythm Automotive, GC4415 was a fitting addition to its machining process.

Both grades contain Sandvik’s second-generation Inveio coating technology.

The material’s surface has a unidirectional crystal orientation. Each crystal lines up toward the cutting edge, creating a strong barrier that improves crater and flank wear resistance. Heat also is led away from the cutting zone more quickly, which keeps the cutting edge in shape for longer time in cut.

“GC4415 and GC4425 can machine a higher number of pieces while contributing toward extended tool life, eliminating sudden breakages, and reducing reworking and scrap. For THK, the GC4415 insert is the remedy to its turning troubles,” said Rolf Olofsson, product manager at Sandvik Coromant.

Driving Forward

Since introducing GC4415 to its machining operations, THK has seen shop floor productivity change for the better. In fact, because it runs at higher cutting rates, THK witnessed an 11 per cent increase in productivity as soon as operators started using the insert.

During the first four months of 2021, THK used roughly 3,800 of the previous insert grade. When the GC4415 grade was introduced in May 2021, the workshop used just 3,000 of the new inserts in the same time frame—an 18 per cent decrease in the number of inserts used, which reduced overall cost per part.

Change isn’t just about numbers, however.

“On the shop floor, our operators are happier, as they can focus on loading parts and not having to worry about frequent tool changes or chip jams,” said Dabrowski. “The new grade has helped save 194 hours of production time per year.”

Following the success of the GC4415 insert grade in machining vehicle front lower tension arms, THK Rhythm Automotive now plans to test and introduce the grade in other parts of its production line, such as ball studs and ball joints.

THK Rhythm Automotive, www.thk-rhythm-auto.com

Sandvik Coromant, www.sandvik.coromant.com

GC4415 and GC4425 carbide inserts from Sandvik Coromant have a broad range of applications and are recommended for both continuous and interrupted cuts.