Motion co-ordinator is at the cutting edge

Seeking a low cost but totally reliable motion control system, Kidderminster Engineering Services (KES) chose a Trio MC202 motion co-ordinator for its new cutter grinder machine.

Seeking a low cost but totally reliable motion control system, Kidderminster Engineering Services (KES) chose a Trio MC202 motion co-ordinator for its new cutter grinder machine.

Operating from a custom-built facility at Kidderminster, KES offers specialist design and manufacture of production machinery systems for applications where standard machines would be unsuitable.

The facility houses a very wide range of lathes, millers, CNC systems, borers, grinders and associated equipment.

Such a large number of machines means that the task of maintaining cutting tools is considerable.

Stocks of tools have to be large enough to allow for those out of service awaiting regrinding or in transit to and from the external cutter grinder company, adding substantially to inventory and maintenance costs.

Any tool damage or excessive wear is also, of course, most likely to occur when a particular job is urgent and no backup tool is available.

When the cost and time delays involved in regrinding cutters and end mills became uneconomic, KES Managing Director Tony Pardoe decided to use his considerable experience to devise a home-grown solution.

"We needed a machine which would be very simple to operate, easy and quick to set up, and which could be used on the shop floor to save time and the inconvenience of sending milling cutters and slot drills away for refurbishment", he said.

"We balanced the desired capabilities of the machine against normal demand and came up with a design which will regrind 99% of all our cutters, yet which costs a fraction of the price of the specialist systems used by outside agents", continued Pardoe.

"Our existing core business had produced a very good working relationship with Lawrence Mummery-Smith at LMS ServoTechnics, who usually programs our more complex systems and supplies the Trio motion co-ordinators we normally employ".

"It was natural, then, that we asked for his assistance in developing a cutter grinder that could perform a wide range of tasks to high standards of accuracy and still be exceptionally easy to use".

"Working together, we decided to use a semi-automatic digital system instead of the potentially unreliable finger method which depends so much on the operator's personal skills and experience".

LMS ServoTechnics supplied a Trio MC202, a compact DIN rail mounted motion co-ordinator based on Trio's proven high performance 32bit DSP technology.

This unit has been designed to provide a compact, cost effective solution for OEM applications.

The MC202 features two axes, the first of which can be configured for either servo (with encoder feedback) or stepper (with step/direction outputs) control.

The second axis may be either a reference encoder or a stepper axis.

A Trio membrane keypad was chosen as the HMI, allowing the operator to answer a menu of questions, which makes setting up a simple process.

The keypad and control system are housed in the base of the cutter grinder, below the working area.

The sharp end consists of a grinding head and motor mounted on a hand-operated slide so that the wheel can be moved horizontally across the machine.

The interchangeable grinding wheel can be angled to suit the requirements of the cutter profile.

The whole assembly moves vertically on a second slide.

Cutters are held in a collet chuck driven by a closed loop servomotor mounted on a third slide assembly linked to a digital linear encoder from Newall Measurement Systems.

Operation is simply a matter of mounting the cutter, locating one of the flutes horizontally and positioning the grinding wheel at the correct angle and height.

Through the keypad, the machine is informed of the number of flutes on the cutter and the required grinding wheel speed.

The display will prompt the operator to move the inactive grinding head along the cutter, establishing the precise length of flute to grind.

Returning the head to its start position, the semi-automatic part of the process can be initiated.

Here the grinder is run up to speed, engaged with the first cutter flute and the head moved along the cutter.

Using data from the linear encoder, the MC202 motion co-ordinator rotates the mill or slot drill to maintain the precise alignment necessary to achieve a successful cutting edge.

When the grinding head is returned to the start position, the workpiece is automatically rotated to the next flute and the process can be repeated until all flutes have been machined.

In this way, end mills, milling cutters and slot drills can be refurbished within a few minutes by any competent staff after minimal training.

"This machine has proven so successful in our own business, we have now decided to offer Mark 2 versions for sale", commented Tony Pardoe.

"KES cutter grinders should appeal to any engineering workshop that needs a fast and simple way to resharpen cutters along the full length of the flutes with no scrap".

"Thanks to LMS ServoTechnics and the versatile features of Trio's motion co-ordinators, we have achieved an exceptionally reliable machine which will reduce cutter refurbishment costs for an economical price".

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