There is a small threaded SS part made at CAM-C Engineering that would worry the life out of lathe setters and inspection unless the most suitable CNC lathe could be identified to do the job.
There is a small threaded stainless steel component produced at CAM-C Engineering that would worry the life out of lathe setters and inspection because of the 10 micron tolerance required over the outside diameter of the special form thread. So when it came to checking out how good the contending lathes for an order to make these parts were, CAM-C decided machining trials had to be the order of the day. As joint owner Mike Evans explains, Colchester put a Tornado A50 CNC lathe, fitted with the 'Lights-out' unmanned turning package, through its paces in the Heckmondwike factory test area and over a 24 hour period, the tolerance drift on the outside diameter of the thread never exceeded +/-2 microns.
Having then ordered a Colchester A50 Lights-out package for the Williams Town Rhondda factory from Colchester Sales Southern Technical Centre, RK International of Erith in Kent, Evans maintains even when they machine batches of up to 2,000 of these special screws: 'The machine never causes any need for concern.' Supplying tight tolerance precision engineered components to a number of top flight scientific and laboratory instrumentation manufacturers, CAM-C Engineering is often asked to perform what a normal subcontract operation would regard as the near impossible.
But, the company maintains, key to its capability is its investment in skill and machine tools.
Even with its reputation of high class precision component manufacture, South Wales-based CAM-C Engineering is more than happy to be known as a jobbing shop.
As Evans, explains: 'We are a jobbing shop, and work with just a few really good customers.
They may take some time to find but then we form a very close relationship.' CAM-C's well equipped machine shop in Williams Town, was set up by Mike Evans and his business partner, Jeff Geraci.
Collectively they have a wealth of experience, cultivated from very different engineering backgrounds but both are very familiar with difficult materials, precision and tight tolerances.
Jeff Geraci's experience was generated predominantly from a toolroom bias, making small quantities of intricate parts from hardened materials while Mike Evans was heavily involved with the volume production of very high tolerance components in often difficult materials.
Evans explains how the two of them normally quote for new jobs between them: 'I quote for the turning element, while Jeff focuses on any prismatic machining and then get together to determine how long the job will take.
Because we have such a close relationship with our customers we sometimes even try a job out at the quotation stage because we want to be sure that the customer will be satisfied and that we can complete the work on time and for the price.
We're not known as the cheapest, but our reputation is built upon a very thorough standard of work and timely delivery.' Although it began as a small order, the success of one of CAM-C's customers, in the production of gas analytical instrumentation, prompted the investment in the Colchester A50 CNC lathe.
Explains Evans: 'Initially this customer was struggling to find a supplier that could meet the level of quality on a stainless steel threaded component, especially because the quantity was very low.
Due to the fact we were willing to work at the job and able to achieve the tolerances required on an existing manual lathe, we then received a major influx of work which meant we were working up to 96 hours a week on this order.' This contract then led the two partners to seriously look at a CNC lathe which would be stable enough to maintain the tolerances required and was able to run consistently in a limited manned situation.
They decided to visit the MACH 2002 show at the NEC in Birmingham, and thoroughly investigated all of the turning centres that were within budget and it finally came down to a choice of just two machines.
Says Evans: 'I arranged to visit both suppliers to check out our stainless steel part being cut.
It was unbelievable that one of the demonstrations was such a complete washout, the machine could not catch the parts which are relatively short, so we could never confirm the accuracy on the last part cut bearing in mind it was an automatic cycle.' 'By complete contrast,' Evans reveals, 'the Colchester Tornado demonstrations initially held at RK International's showroom in Erith and later as a full trial at the Colchester factory in Heckmondwike was superb.
Although it is small, the component is fairly complex with a special high tolerance thread and three chamfers based around a critical undercut groove formed half-way down the part.' Evans continues: 'This groove is important because it acts as a guide and location pickup point for the automated test laboratory equipment that uses the finished assembly.
Also, the modified external thread has to be turned to provide a light, press fit into another part of the assembly.
The engineering solution to achieve the accurate generation of this thread form was where Colchester won the day.' The Colchester 'Lights-out' package comprises a fully integrated MBF 1000 bar feed system, programmable from the machine's Fanuc control, swarf conveyor, on-board Renishaw probing for size control and parts catcher.
The 12 station VDI turret machine also has work scheduling software and tool monitoring based on power sensing which can initiate sister tool replacement.
Another influencing factor in the purchasing decision was what CAM-C describe as the double backup available with both RK International and Colchester Sales which are both able to provide support.
Evans confirms: 'We have established a good relationship with RK and 99 per cent of the time any questions are answered directly on the telephone.
We did have a probing problem which caused the barfeed to reference.
Even though the Colchester service engineer quickly solved the problem, both Colchester and RK have made follow-up courtesy calls to ensure everything is still OK.' Most batch sizes produced by CAM-C Engineering seem to be around 10 parts.
Materials machined include stainless steel, brass, aluminium and a small quantity of titanium parts for a customer in the instrumentation industry.
As Evans outlines: 'Because we know our customers for lower volume parts we tend to group three months worth of production together and then link those parts to other batches we can produce out of the same size raw material.' Here, the 'Lights-out' machine package software has proven to be a boon because it has a scheduling system in the Fanuc control for up to 10 component types which allows the different parts to be nested in the same bar of material.
He adds: 'It suits us down to the ground, because a lot of our parts are similar in size and we can use similar tooling, to cover threads, holes and counterbores.' By clever planning, relatively low batch quantities of say 10 or 15 are easily turned into more economical batches of 100 or even 150 parts which are set during the day.
'Once we are confident of our tooling and programming, the machine is more than capable of running overnight.
We don't just use 'lights-out' turning, we live it, which gives us tremendous economies and machine utilisation,' insists Evans.
CAM-C purchased the A50 with a chuck to also enable billeted components to be produced.
The largest part turned so far is a 68mm diameter aluminium soil probe cap using the MBF 1000 integrated barfeed.
At the other end of the scale, although Colchester's recommended minimum bar size is 6mm, in order to prevent the push rod in the barfeed system fouling, the company has successfully run batches of parts below 5mm diameter.
It is also common to work close to the chuck to prevent any material deflection.
Indeed, by using special toolholders the tool is prevented from striking the chuck.
And, Evans maintains: 'The Colchester developed parts catcher works without any problems even on the smallest parts!'
