Mollart Engineering bags £1.25 million US order
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Mollart Engineering has won a four-machine turnkey installation order from America, worth £1.25 million, for a deep hole drilling facility for automotive engine valves produced at a rate of four per minute. The operation is performed prior to subsequent sodium filling of the hole, which improves heat dissipation.
"This was a significant contract to win against five other machine tool suppliers all very keen to take the business," said Mollart Engineering managing director Guy Mollart, adding. "However, they could not compete against our four-spindle VDM Microdrill concept with fully integrated autoloading; its vertical up-drilling method and specially developed collet chucks that counter-rotate the part to the rotation of the drill. This method ensures ultimate levels of concentricity, even when producing four parts in a minute cycle.
"On machine trials, we were able to establish a concentricity within 0.1 mm TIR, surface finish within the customer's 6R specification, and a CPK value of 1.6 for the 3 mm diameter hole that is required to be produced 70 mm deep in each valve stem. Following deep hole drilling, each valve will have a sodium pack inserted in the hole and a cap friction welded to the stem prior to finish grinding."
The VDM Microdrill machine is widely used in fuel injection, medical and fluid power industries for precision holes and for multiple hole drilling in a single cycle. The machine has a capacity between 0.5 mm and 6 mm diameter in both two and four-spindle configurations. Fitted with an optional programmable CNC cross-table, holes of different sizes can be progressively drilled, or multiple holes drilled in a component, with no need to unclamp the part.
The American order involves the simultaneous loading and drilling of four valve stems at a time with the cycle partially overlapped with the drilling operation to minimise the production time.
As part of the proven process, Mollart is supplying the latest solid carbide coated gundrills, Type 113, developed by Botek, the company's tooling partner. Depending on the process, the new drill type is able to be run at penetration rates up to 800 times faster than conventional drills and to a depth-to-diameter ratio of 80:1. In this application, the drills are using through-tool neat oil coolant and will be run at a penetration feed rate of 70 mm/min.
