Mill-turn centre machines bike parts in one hit

Mill-turn centre cuts out the handling operations so that a mountain bike parts manufacturer can operate more machines with the same number of people, while reducing costs and improving quality.

Already a Hitachi Seiki user, mountain bike parts manufacturer Hope Technology, invested in a Mori Seiki NL2500 SY single turret lathe with Y-axis and direct drive milling spindle to manufacture cassette bodies and handlebar clamps.

Company founder, Simon Sharp said: "This machine is working 24 hours per day, five days per week, manufacturing thousands of parts from aluminium bar." Previously, the cassette body required four operations, starting on a 2-axis lathe and transferring onto a milling machine.

* One operation - on the Mori Seiki, the parts are finished in one operation.

Sharp continued: "Our aim is to cut out the handling operations so that we can operate more machines with the same number of people which will, in turn, reduce costs, create better working conditions, and improve efficiency and quality." Costs have been reduced by around 50% with one hit machining.

Furthermore, quality has improved by approximately 15% through the elimination of size variations caused by refixturing the component before each new operation.

Hope Technology has now invested in a second Mori Seiki NL2500 SY to manufacture hub bodies.

Sharp commented, "This second machine is a continuation of our efforts to optimise our machining processes, a policy we have been pursuing for the last three years." Both machines are fitted with a Hydrafeed bar feeder and part unloader to minimize the attention required to keep them running smoothly.

When choosing a machine, Sharp was particularly impressed with the direct drive motor located in the turret of the NL2500 SY.

"Both the machine and turret are much more rigid and we can achieve higher spindle speeds.

If you listen to a lathe with belts and a gearbox you can appreciate how low the vibration levels are on the NL." Mori Seiki achieved machine rigidity through static and dynamic analysis of the machine's structure during the design phase.

This resulted in 100% greater contortional rigidity for the bed and 50% greater for the spindle when compared with the previous model.

Slideways were also constructed 30% wider than on conventional machines, making them the largest in their class.

The company selected single turret machines to provide flexibility and continuity.

Sharp explained: "We have capacity for up to 50 tools on the one turret, which is more than enough for our needs.

Having a single turret also significantly reduces the cost of the machine and, although cycle times are a little longer than with a twin turret machine, both programming and setting are simpler.

Furthermore, having two identical machines gives us the flexibility to move parts between machines, helping us to achieve our production targets." Around 20% of the products produced on the two Mori Seiki machines involve milling, so the 40Nm torque available at the milling spindle is invaluable in helping Hope Technology to optimise its manufacturing methods.

* Accuracy - Sharp is pleased with the accuracy of the Mori Seiki, which keeps within the 0.01mm tolerances demanded by his products.

He is also impressed with the thermal stability of the machine.

He said: "We don't get any size variation while the machine is heating up, which is a great advantage to us." Mori Seiki uses a covered bed, and oil cooling jackets to maximise thermal isolation.

Sharp concluded, "We are anticipating at least a fifteen year life for the Mori Seiki machines and payback within five years.

We purchased our Hitachi Seiki machines in 1992 and they are still going strong.

We expect to get the same reliability from our two NL2500 SY machines".

* About Hope Technology - located in Barnoldswick, Lancashire, UK, Hope Technology is a leader in the development and manufacture of durable, high quality cycle components which are sold in 28 countries around the world.

Formed in 1987 by keen mountain bikers Simon Sharp and Ian Weatherill, the company initially started as an engineering subcontractor, making parts for the aerospace, automotive, and toolmaking industries.

In 1989 they saw an opportunity to make parts for cycles, producing some of the first hydraulic disc brake assemblies.

With little competition at the time, the company grew rapidly, and now employs 65 people, designing and manufacturing an innovative range of products including hubs, wheelsets, lights, stems, headsets and quick release clamps.

Sharp said, "We aim for the top end of the market, our trademark is machining parts from solid rather than using mass produced castings." Its success in the cycle market led the company to phase out its subcontract business in 2003/4, concentrating all its efforts on new products and more efficient manufacturing methods.

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