Metrology software products ltd (MSP) – who are exhibiting on Stand H19-338 at MACH 2018 – worked with Renishaw to increase Doncasters Precision Castings’ productivity by 100%.
Doncasters Precision Castings is a leading manufacturer of industrial gas turbine airfoils. The company has seen increased demand for its machining services, which has led to a significant investment of over £2 million in Mazak products.
The company previously used three-axis machining centres, but the processes were time-consuming and required highly skilled operators and hard fixturing. A typical nozzle component’s cycle time, including setting and machining, was four hours, which exceeded the capacity available to meet the increased demand. Furthermore, hard fixturing was viewed as expensive and obsolete by the engineering team.
Therefore, the company invested in three Mazak VORTEX i-630V/6 vertical machining centres. As part of the investment, the machines were equipped with Renishaw RMP600 high-accuracy probes, featuring patented RENGAGE™ strain gauge technology. During initial discussions, it was also recognised additional support would be required from associate company, MSP.
The challenge was to improve right-first-time machining rates and, in doing so, eliminate any potential for errors to arise and increase overall productivity.
Doncasters’ Engineering Manager Ollie Macrow explains: “When dealing with superalloy castings worth thousands of pounds, the machines must be correct.
“Costs are another concern. In addition to the cost of the casting, is the time that is lost and the relatively high cost of tooling. Additionally, some components are not reworkable, so if it’s wrong after machining, it’s scrap. Our challenge was to figure out how to probe the part successfully without hard fixturing.
“Hard fixturing is expensive and requires high skill levels. Furthermore, if a fixture becomes damaged you can’t machine as the part can’t be aligned, so fixtures have to be maintained to a high level, which adds time and cost. Our challenge here was to replace these fixtures with simplified, modular-type systems”.
The company also had limited probing experience, so Renishaw’s input would be vital.
Furthermore, production targets had to be met and although, the new machines had brought a bulk of machining in-house, there was still a requirement to sub-contract out some secondary operations. By improving productivity, the aim was to bring these operations in-house.
The Renishaw Applications Engineer recognised MSP’s NC-PerfectPart and NC-Checker software combined with the RMP600 probe would provide the best overall solution.
This combination of hardware and software identifies errors in part positioning and a machine’s geometric performance before a part is cut.
The initial step is to ‘map’ the machine tool, creating a benchmark. NC-Checker checks the performance of the probe before carrying out five-axis checks of the machine tool. This ensures every aspect of probing and machining performance is within set tolerances prior to part setup and metal cutting.
The machine check can run regularly to ensure the machine continues to operate within set parameters. NC-PerfectPart solves problems created by poor part alignment on the machine tool. This is of particular importance on components with complex shapes and those subject to five-axis machining. Setting up these parts can be time-consuming, and difficult to achieve accurately and consistently.
This is overcome by probing the part with the RMP600 using a program created from the component’s CAD file. From this measurement, an alignment is created to eliminate errors in part positioning.
This is uploaded to the machine control and compensations are automatically calculated to produce a part program perfectly aligned to the part. Set-up is automated, meaning fixturing is no longer critical, manual set-up error is eliminated and time required to set components is reduced to minutes.
Furthermore, elements such as material condition, pallet loading systems and temperature, can be accounted for early on, further reducing the risk of producing bad parts.
After metal cutting, NC-PerfectPart confirms the accuracy of the finished component before it is removed and inspected on a CMM.
Before the addition of the RMP600 and MSP software, it took four hours to set and machine a typical industrial gas turbine nozzle. Now they can be probed, machined and checked in under two hours – a 100% productivity increase. On complex components, machining could take up to eight hours and required a highly skilled operator to oversee the process.
These parts are now produced in the same two-hour cycle as simple parts, generating even greater savings. Commenting on the success, Ollie Macrow explains: “When we bought the machines, we sat with Mazak and said “How are we going to do this?” They didn’t think it was possible with our current set-up but Renishaw and MSP provided the solution we needed. Our customers are giving us positive feedback as we have greatly improved our right-first-time pass rate. I genuinely feel we would not be successfully machining castings without the help of MSP and Renishaw.”
This content was supplied by Metrology Software Products Ltd