Sandvik Coromant comes to the rescue for THK’s Machining Problems

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Tillsonburg has come a long way since Canadian country music legend, Stompin’ Tom Connors thrust the small Ontario town and its tobacco fields into the spotlight with its namesake song. Today, Tillsonburg is part of a thriving automotive region, home to the THK Rhythm automotive plant that serves global manufacturers including BMW, Ford, and Daimler Mercedes Benz. A tough, competitive landscape meant THK Rhythm needed to make its offering stand apart from competitors. To give its products the edge, the company enlisted the support of Sandvik Coromant and its new steel turning grades.

The THK Rhythm automotive plant specializes in suspension components found in vehicles worldwide, along with ball joints and ball studs for these components. Being a global automotive player demands stringent quality and cost-optimization measures, which is evident in the THK facility. THK’s quality policy, which is prominently displayed at the plant’s entrance, reads: ‘right the first time, right every time, continually improve’, which is more than just a catchy mantra. Several manufacturing improvement practices evidence this policy, including Kaizen, Japanese for continuous improvement, which focuses on optimizing efficiency, productivity, and overall equipment effectiveness (OEE). 

Despite THK’s crystal clear efficiency goals, reaching productivity targets and controlling cost was a challenge when producing the front lower tension arm, a component that goes into the suspension assembly of a car. The machining process was a challenge for THK Rhythm. “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, a process engineer at THK Rhythm.  

Adrian Dabrowski

This component is made of a forged ISO P steel that is particularly abrasive, with high tensile strength. Machining this part requires a specialist tool with a number of inserts that are staggered or stepped which means they are not all of the same diameters. The original machining process for the front lower tension arm was designed to make 140 parts per tool, however, THK could only produce about 92 pieces on average before one of the inserts on the largest diameter failed, which caused the entire tool to fail.  

Frequent failure meant operators had to change tools far too often. The machines in the THK Rhythm workshop are set up in a way that if one tool breaks, a spare tool is brought in automatically so that the machines can keep running. With frequent tool failures, however, there were not enough spare tools to keep production flowing. Chip control, a vital consideration for any steel turning operation, was also 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,” revealed Gary Martin, a machine operator at THK. “These chips were sharp and could cause finger cuts and injuries” he added. 

Using the previous inserts there were a lot of downtimes, which made meeting daily productivity targets difficult. 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.” 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,” continued Dabrowski. “On these days, downtimes were as frequent as three-to-four times per shift per machine.”  

The search for a solution 

In search of the right solution, THK tried to adjust the machines on a daily basis, fine-tuning feed rates and revolutions per minute (RPM). The team also tried out different inserts and geometries from a couple of tool suppliers, but nothing hit the mark. That was until THK turned to Sandvik Coromant.  

Part of the global industrial engineering group Sandvik, Sandvik Coromant is at the forefront of manufacturing tools, machining solutions, and knowledge that drive industry standards and innovations demanded by the metalworking industry now and into the next industrial era. Educational support, extensive R&D investment, and strong customer partnerships ensure the development of machining technologies that change, lead and drive the future of manufacturing.  

Sandvik Coromant, to resolve the conundrums of THK added two high-performing carbide insert grades, GC4415, and GC4425, to its existing range at the end of 2020. The 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 are needed. For THK Rhythm, GC4415 was a fitting addition to its machining process. 

Both grades contain the second-generation Inveio® coating technology. “What makes this tool coating particularly unique is that it can be examined at the microscopic level,” explained Rolf Olofsson, product manager at Sandvik Coromant. The material’s surface has a unidirectional crystal orientation. Each crystal lines up towards the cutting edge, creating a strong barrier that improves crater and flank wear resistance. Heat is also led away from the cutting zone more quickly, which keeps the cutting edge in shape for a longer time. 

Rolf Olofsson

“GC4415 and GC4425 can machine a larger number of pieces, while contributing towards extended tool life, eliminating sudden breakages and reducing reworking and scrap. For THK, the GC4415 insert is the remedy to its turning troubles,” continued Olofsson.  

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% increase in productivity as soon as operators started using the insert. During the first four months of 2021, THK used roughly 3,800 inserts of their previously-favored grade. When the GC4415 grade was introduced in May 2021, the workshop used just 3,000 of the new inserts in the same timeframe — an 18% decrease in the number of inserts used, dramatically improving overall cost-per-part. 

Change isn’t just about numbers. “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,” concluded Dabrowski. “The new grade has helped save 194 hours of production time per year. Thanks to GC4415, the THK Rhythm workshop now experiences far less downtime and more reliable production.” 

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

The THK Rhythm automotive plant specializes in suspension components found in vehicles worldwide. When reaching productivity targets and controlling costs was a challenge for the company, it turned to Sandvik Coromant and its steel turning inserts. Before, tool failure was a frequent challenge for THK. Now, with the GC4415 steel turning insert, THK has witnessed an eleven percent increase in productivity and an 18 percent decrease in the number of inserts it needs to use. To tackle more such issues that you face at your workshop with the help of Coromant’s range of steel turning grades that can transform your machining process visit here: www.sandvik.coromant.com. 

 

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