PCD tool production at STF Precision

German grinding/erosion machine company has been key to the growth of American tool manufacturer

Posted on 23 Dec 2019 and read 883 times
PCD tool production at STF PrecisionThrough the 1980s and into the early 1990s, Ted Ford was working as a general manager for a company that specialised in single crystal diamond (SCD) tooling and was heavily involved in the super-finishing sector.

However, mergers and acquisitions gave him the opportunity to buy the diamond tool division from Norton Abrasives, and in 1993 he formed STF Precision.

Unlike most cutting-tool manufacturers that graduate from standard cutting tools and progress to high-end product lines, STF Precision used the expertise it had gained making ultra-precision super-surface-finishing SCD tools to enter the diamond-coated and PCD cutting-tool sector; later, it also ventured into the solid-carbide cutting-tool market.

The ‘journey’ from SCD to PCD started in 2001, when Ted Ford sold the business (based in Arden, North Carolina) to his son Jason, who decided to extend the product portfolio.

He first bought a number of wire-cut EDM machines, followed by a PCD erosion machine from the German company Vollmer, which has a UK subsidiary in Nottingham (www.vollmer-group.com).

Jason Ford says that this machine was ‘key to changing his company’s fortunes’.

“We recognised the opportunities offered by erosion grinding machines from Vollmer, particularly for developing fluted PCD tooling of the type needed for machining the ever-increasing amounts of composite materials being used by the aerospace industry.

“We wanted to ‘loosen the stranglehold’ that some competitors had on this market segment, and it was Vollmer that helped us to achieve this.

“In addition, we were a relatively small company at the time, and Vollmer gave us favourable financial terms to get us our first machine.”

Despite having the first Vollmer QXD200 machine in the USA (in 2006), STF Precision initially struggled to break into the aerospace sector.

However, the flexibility of this machine allowed the company to extend its ‘offering’ to the automotive market.

“Being a business known for its micron precision, we began producing cutting tools for piston production.

“With the ability to produce tools to an accuracy of better than ±2µm, with form angles to ±15min, we found a niche manufacturing tools for machining high-silicon-content materials for the automotive market — initially with globally recognised Tier Ones and later with major OEMs.”

Journey of growth


The arrival of the first Vollmer machine was one of the cornerstones for growth at STF Precision, as Jason Ford highlighted: “From 2001 to 2008, we had grown from a company with five staff and a turnover of $750,000 to one with a turnover of $3 million.

“Following continued investment in Vollmer technology and automation, we now have a turnover of $12 million and more than 70 staff — and we are running machines unmanned overnight.”

Following the first QXD200 machine in 2006, another two QXD200 machines were installed, in 2008 and 2010.

These were used for the production of milling cutters, reamers and drills, and a larger QXD250 was installed in 2012.

PCD pic 2Jason Ford said: “The wire machines we purchased before the arrival of Vollmer’s required a fourth-axis rotary head for processing round tools.

“The Vollmer QXD200s and QXD250 were at least 30% faster, more reliable in operation and more accurate.

“We also specified the QXD machines with 29-tool-station loaders, to give us unmanned automated production.

“Indeed, we more than doubled our production capacity, with just a ‘skeleton’ second shift to load machines at evenings and weekends.”

STF Precision’s work for the automotive market saw the company making PCD form tools with increasingly complex geometries, prompting the installation in 2014 of its first Vollmer wire erosion machine.

“Our customers were requesting more-complex internal form tools and large-diameter milling cutters.

“The solution was a QWD760 machine, which I regard as the most accurate wire machine available for processing cutting tools.

“This was followed by a QWD760H in 2016, which was specified with a 12-station automated loader; with our complex geometry automotive tools taking upwards of 3hr to process, the 12-station QWD760H can run for days without operator intervention.”

By designing and developing solutions in close co-operation with its customers, STF Precision’s automotive portfolio has evolved beyond bespoke piston production tools to specialised tools for engine blocks, cylinder heads, transmission casings and other powertrain, transmission, axle and suspension parts.

The automotive industry now makes up more than 65% of the company’s turnover, although the precision, productivity and flexibility of the Vollmer machines have enabled STF Precision to achieve growth in the aerospace market.

“In recent years, this has grown to make up 25% of our turnover, and we see great potential for growth here to continue.”

Increasing variety


STF Precision says it sets itself apart from other vendors by distancing itself from standard catalogue items that are manufactured in high volumes.

Some of the products available include PCD single- and multi-groove tools, PCD and CBN indexable inserts, SCD inserts, form tools, custom diamond tools for NASA, knife tools, PCD and SCD rotary tools (these include tipped drills, end mills, reamers, countersinks, ball-nose tools, multi-step drills, reamers and counter-sinking tools), automotive wheel tools and CBN indexable inserts.

The company also manufactures a complete selection of solid-carbide form tools, end mills, step drills and reamers to specific user requirements — plus it uses a range of turning and machining centres for producing monoblock and indexable-insert tool bodies.

PCD pic 3After seeing significant progress with its solid-carbide tooling department, STF Precision bought a Vollmer Vgrind 160 with HP160 pallet loader in 2017.

Jason Ford said: “We bought the Vgrind 160 because it has the flexibility to pocket PCD tools and also to manufacture complete solid-carbide tools.

“Our initial thinking was to install the machine for pocketing PCD tools, but growing demand for our carbide tools has seen the Vgrind dedicated to producing carbide drills, end mills and reamers in diameters from 2.5 to 25mm.

“From a PCD perspective, the Vgrind is now a ‘back-up’ to the QXD and QWD machines.

“We are now supplying over 300,000 PCD inserts a year — and producing hundreds of bespoke PCD cutting tools and brazed tools every month.

“This number of PCD tools doesn’t include the on-going servicing of PCD tools for existing customers.

“However, it is the solid-carbide market that is growing in volume. The carbide business is lower-cost and higher-volume; we are already manufacturing a few thousand end mills, reamers and drills every month.”

Last year, STF Precision visited the Vollmer VDays event; impressed by the latest VPulse 500 with next-generation wire erosion technology, he immediately bought one.

Featuring the tried-and-tested Vollmer VPulse EDM erosion generator, but incorporating it for the first time into wire erosion, the VPulse 500 offers ‘high material removal rates or optimised surface quality’.

Furthermore, it was specified with an HR external workpiece storage and automation system, which accommodates up to 16 tools with a maximum diameter and length of 300mm and 500mm respectively.

In conclusion, Jason Ford said: “Vollmer has been instrumental in our growth, and the company always seems to have a solution to our tool-manufacturing needs, however diverse.

“Recently, an industry contact asked if we could produce circular saw blades up to 430mm in diameter for cutting 8 x 4ft glass fibre boards for the construction industry.

“We couldn’t, but the opportunity was sufficient to justify buying a Vollmer QM ECO Select.

“This five-axis QM erosion machine is ideally suited to producing and re-sharpening PCD- and TCT-tipped saw blades.”

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