Case Study

Case Study: Hope Technology Chooses Nakamura For One-Hit Machining

A combination of enthusiasm and innovation has helped UK-based Hope Technology transform itself from a general subcontractor into a world-leading brand in the mountain bike aftermarket. As part of its long-term manufacturing focus Hope has recently invested in a Nakamura-Tome WT-150 twin-spindle twin-turret lathe supplied by Turning Technologies. The new machine, which is fitted with a robot part-loading system, is part of Hope's drive for continuous improvement of its processes - with the emphasis on high-quality, repeatable and productive one-hit machining.

Simon Sharp and Ian Weatherill, the co-founders of Hope, started their careers as apprentice toolmakers at Rolls-Royce and went on to set up their own subcontracting company. They had always been interested in motorcycle trials riding and mountain bikes, so after a few years in business it is not surprising that they turned to making what interested them.

"We could see that the technology on a trials bike was eventually going to be applied on a mountain bike and saw an opportunity," says Simon. "We made a front hub first, went to a few mountain bike races and it took off from there."

Hope now makes and markets a range of hydraulic disk brake systems for mountain bikes, as well as stand-alone hubs and other ancillary equipment.

"A lot of the mass-produced products on the market are cast, but we believe that machined parts are stronger, better balanced and more attractive - all our hubs are machined from billet," says Simon.

As well as quality, Hope is also focused on process improvement by reducing production times, handling, and the number of operations.

"That's why we bought the Nakamura WT-150," says Simon. " We are making 30,000 to 40,000 hubs a year and we will now be able to do them in one go rather than two operations as we were doing it before. This is our first twin-spindle twin-turret machine, but we needed both turrets because there is a lot of machining on both ends of the part. With twin turrets we can balance the operations to get the best cycle time."

He explains that as well as turning, drilling, tapping and de-burring, each hub calls for a significant amount of milling, making the Y-axis a necessity.

"We are literally starting with a billet and ending up with a finished part that can go straight into anodising. It has cut out a lot of dead time," he says.

It takes about 7-8 minutes to produce a hub so the robot is standing idle quite a lot of the time, but it is still cost-effective because there is no downtime and no need for an operator to keep loading parts. But to automate effectively it is vital to have the right machine tool to build the system around, and Simon says it was Nakamura's good reputation for quality and process stability that led him to decide on the WT-150.

"It is a machine designed for production, and what we really like about it is that it is very accurate. We don't have to adjust the offsets very often and the repeatability is very good. That's important to us. We talked about putting probing on the machine, but realised that we didn't really need it. If you are going to adopt unmanned running you need to be sure that the process is very stable."

Before deciding on the WT-150 he looked at a variety of other ways of doing the job, including a vertical lathe loaded with billets. The problem there, he says, was that you have to have turnover stations and it can get quite complicated when you try to locate the second side. He also looked at a gantry loading type of machine, but that was quite an expensive option and not as flexible as using robot loading on the Nakamura.

"With the WT-150 you don't have to worry about locating the part as you are loading a plain billet and the machine knows the orientation it is in when you transfer it between spindles," he says.

For the hubs the robot is loading cut billets. 65mm diameter and, as Simon points out, if you wanted a barfeed machine to cope with this diameter it would have to be a big machine.

"A bar-fed twin-turret machine to do this job would have to be a pretty big piece of kit and a lot more expensive as well. And once you start having to turn bar that size all the spindle speeds start to get much slower. We can run the same size part faster on a smaller machine."

SOURCE: Sticklebacks Communications Ltd