A-Tap offers high process reliability across a wide range of materials
Dieter Prinz | OSG Germany
Multi-purpose isn’t usually associated with high performance, especially with cutting tools. When it comes to taps, tool geometry and substrate are commonly designed specifically for the material to be processed. Even though Brinke & Breuer, a company active in tool making, mechanical engineering and fixture construction, works with a broad range of materials such as aluminum, copper, brass, mild steel and tempered steel, the need for new threading tools never surfaced as a topic.
Brinke & Breuer was established in 1995 with a focus on metal works for construction. Gradually, its business domain shifted to traditional metal and mechanical engineering. In 2011, tool making for injection moulding was added to Brinke & Breuer’s portfolio. The manufacturing range was further broadened by acquiring two 5-axis machining centers and water-jet cutters due to new market requirements.
Today, Brinke & Breuer’s customers are not limited to a specific industry, but stem from a variety of industry sectors, such as automotive, supply industry and pump manufacturing among others. One of Brinke & Breuer’s strengths is custom and small batch part manufacturing. The tools used at Brinke & Breuer until then were, apart from a few exceptions, yielding excellent results. Changes, however, came about when the company needed to machine electrolytic copper (E-Cu), a material often worked with in Staudt, Germany, where the company is located. According to the owner, Jens Brinke, it was this material that started the relationship with OSG.
“We were looking for a 9 mm diameter deep-hole drill for the machining of electrolytic copper with a depth of 300 mm,” said Brinke. “Only OSG was able to deliver a solution to that problem at the time. Starting with this application, we made a full switch to OSG, which includes threading tools as well.”
To Brinke & Breuer, it was not only about the number of holes, but more importantly process reliability. They had given the A-Tap spiral flute tap (A-SFT) a try because the tool had promised high cutting speeds across a broad range of materials on top of long tool life.
OSG’s A-SFT spiral flute tap is an all-purpose tap series designed to simplify tool management and to excel in a wide variety of materials and applications. The A-SFT has adopted a variable helix flute design, which encourages stable chip evacuation and reduces cutting forces. The helix angle changes from the chamfer, where chips are formed, to the flutes, where chips are evacuated. This unique geometry enables greater chip control that can help produce tightly compacted chips for easy ejection from the hole. To accommodate a wide range of cutting conditions, powdered metal HSS and OSG’s patented V coating have been employed in this series to achieve excellent wear resistance.
Brinke’s main concern was the advertised absolute process reliability regarding chip formation and evacuation across a variety of materials at high cutting speeds. It is a major concern mainly due to the fact that threading is usually the last step in the production of high value components, where mistakes would be very costly.
When producing one-of-a-kind or small batch components out of a broad variety of materials, tool life is not the most important factor. Neither is there a need to shave down cycle times. Looking at the range of materials and thread sizes from M2 to M16, tool management can also become a serious issue. On each of the eight machines used during each shift, a minimum of three to four different materials are processed. With this factor in mind, a huge variety in threading tools would have had a negative impact on setup time. Both partners of Brinke & Breuer, Jens Brinke and Michael Breuer, wanted a tap that was economical. And, according to them, it is economical only if you can cut 10 threads with a M2.5 tap into a 1.2379 tool steel at ease. So far, no off-the-shelf tool was able to cut even a single thread into that material.
Better safe than ambitious cutting speeds
On top of ease of use and long tool life, ambitious cutting speeds is also promised by OSG. Speeds up to 70 m/min in 42CrMo are advertised, a feature that is very beneficial at the Brinke & Breuer manufacturing plant.
“The first problem with a lot of different threading tools is educating the employees – when and with which application to use what tool at what speed and which feed rate,” commented Michael Breuer.
“We solved that problem by using the A-SFT, which doesn’t require the cutting parameter to be set individually. But apart from one employee, no one is yet brave enough to approach the ambitious cutting speeds. On the other hand, we know that the slower the speed, the higher the risk of failure and breaking of the tap. We traced that back to the galling of the cutting edges. Fortunately, unlike other taps, the A-SFT is really razor-sharp.”
In order to achieve high cutting speeds, state-of-the-art machines with precise synchronization is a prerequisite. Nonetheless, the A-SFT seems to be paying off at Brinke & Breuer with materials such as soft copper, high-strength aluminium and steels up to 42 HRC. With the 2-shift system, tool wear and failure are reduced to less than one percent, and findings from quality control are also promising. Since December 2013, Brinke & Breuer’s inspection department had compared tap performance before the switch. Thread qualities are checked and necessary rework gets written down. According to their reports, the A-SFT outperforms the already satisfactory old tap in every aspect.