Five Ways HAIMER Shrink Fit Technology Maximizes Value

When you pay millions of dollars for the CNC machines in your shop, don’t you want to receive maximum payback from your investment? Equipment that sits idle costs money; as does equipment intended to run lights-out, that can’t.

Custom Mold and Design, based in Minneapolis, Minnesota, knew accuracy was ultimately a problem hampering their productivity on eight machines that produce small medical components. Most of the jobs they run require cutting tools with diameters smaller than 2mm, working in hardened materials such as P20, S7, A2 and H13 tool steel.

With collet holders, maintaining runout accuracy was a major challenge. Part of the problem was the collet design that allowed dirt and chips to collect and remain in the holder, even after time-consuming cleaning procedures. Even minute particles of debris were enough to create uneven clamping pressure, which ultimately led to inconsistent runout accuracy. This inaccuracy had a direct impact on both productivity (slower machining speeds and rework) and tool life.

The goal was to bring out the full potential of their CNC machines by increasing: 1) accuracy, 2) finish, 3) productivity, 4) repeatability, and 5) tool life. Like many companies, Custom Mold and Design turned to HAIMER shrink fit technology to make it happen. Ten years ago, they purchased a HAIMER Power Clamp Mini with BT40, HSKA-32 and HSKA-63 toolholders to address the aforementioned needs.

“We wanted to run lights out, and the collets we were using just didn’t have the runout accuracy and balance properties we needed,” said Gregg Virnig, the firm’s Hard Milling Specialist. “We bought the HAIMER shrink fit equipment and never looked back.”

Here are reasons why Custom Mold and Design gives such positive feedback on the HAIMER shrink fit system:


“Even a slight error in runout makes a big impact on the smaller parts we make,” Virnig commented. “With the shrink fit, we saw a notable reduction in benching.” The amount of rework needed to bring out-of-tolerance parts back into specification decreased, thereby helping Custom Mold’s throughput by getting the next job in queue on the machine faster.


HAIMER shrink fit technology is so accurate that Custom Mold and Design uses the toolholders for all operations, both roughing and finishing. The improvement in surface finish quality has reduced secondary polishing operation times by 30%.


Higher and repeatable runout accuracy enabled Custom Mold and Design to increase cutting speeds by 10% across the board, resulting in a 10% reduction in cycle times. Furthermore, because extensive cleaning processes for collets and collet chucks were eliminated, tool changeover times were drastically reduced, and machine utilization increased. “With shrink fit, it’s easy,” Virnig mentioned, “you just put the tool in and you go.”


Custom Mold and Design appreciates the fact that HAIMER toolholders have a consistent 0.0001” runout accuracy. No moving mechanical parts means no components to wear out and cause unpredictable accuracy problems. In fact, Custom Mold is still using the first HAIMER tools they bought ten years ago, with no sign of any degradation. They know this because the company etches the purchase date on each toolholder. This means that each holder has been through hundreds, if not thousands of shrink cycles, with performance the exact same as new. And it is this absolute repeatability that helps ensure they can run parts lights-out.

Tool Life

Custom Mold and Design nets significantly more tool life from their end mills in HAIMER shrink fit. This is because the same TIR accuracy that ensures geometric part accuracy also inherently improves the life of the cutting tool as well. Every degree of runout accuracy gained helps further prevent uneven edge wear, thus extending the life of their high performance carbide cutting tools.

Closing in On Perfection

Fine tuning a CNC machine for maximum speed and the capability for lights out machining means controlling a wide variety of elements. The inherent benefit of HAIMER shrink fit technology is that it virtually eliminates the toolholder as a variable for error. This repeatable quality allows operators to establish a solid baseline from which they can really begin to fine tune their machining processes and maximize efficiency.

Originally post from Haimer USA, Link here

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