IMS wins through with CMM for RMI Titanium

Citation

(1998), "IMS wins through with CMM for RMI Titanium", Aircraft Engineering and Aerospace Technology, Vol. 70 No. 3. https://doi.org/10.1108/aeat.1998.12770cab.046

IMS wins through with CMM for RMI Titanium

IMS wins through with CMM for RMI Titanium

Keywords Automation, IMS, Measuring machines

A couple of years ago Harry Klein, quality manager of RMI Titanium Company, Tamworth, went to an exhibition with a budget allocation for a measuring machine and was quite unprepared for the reaction by many in the industry. Far from being welcomed as a herald of the post-recessionary upturn, he had great difficulty in convincing many of the suppliers he approached, to take him seriously.

The fact that International Metrology Systems sales operation IMS (UK) of Swindon did ultimately result in the sale by them of a computer controlled Merlin co-ordinate measuring machine (CMM) as well as the fixtures and, since the installation, the CMM is performing measurements automatically in a few hours, that previously would take two weeks by manual methods.

RMI is the UK subsidiary of an US parent. The company supplies titanium sheet, plate, coil and pipe with around 90 per cent of sales into the aerospace industry. The company keeps around 100 tonnes of material on site, comprising both unalloyed and alloyed materials and is able to supply raw material, as blanks, in virtually any shape and dimension.

It had been decided that a CMM was the best bet for a particular major contract which calls for regular supply of rectangular blanks. There are a dozen specifications, which range in size from 6mm thick × 200mm × 480mm up to 22mm thick × 500 mm × 1,000mm. Each blank has its own serial numbered allocation and is fully traceable back to the ingot.

However, while the dimensional specification on these blanks is not overly tight; the length tolerance, for instance, is from 0.5mm up to 4mm, parallelism and squareness needs to be within 1.0mm. In addition, each rectangle must be flat to within 0.5mm over the whole surface.

RMI manufactures the components from standard sheet and plate using a sophisticated CNC bandsaw. Batch quantities vary between 20 and 120 and according to customer requirements and 100 per cent dimensional checking is a condition of supply.

The IMS Merlin CMM generates fast payback at RMI Titanium

Says Harry Klein:

We calculated that to achieve a satisfactory just-in-time supply regime covering all eventualities we needed the capability to inspect each plate in under four minutes. This time included any handling such as load and unload. It was pretty obvious to us that we needed an automated process and were quite open as to the measuring technology solution that would suit us best.

For that reason Harry Klein went to an exhibition at the NEC, had a look around, spoke to a few people, then wrote to possible suppliers directly after the show. The brief was for a turnkey package including appropriate macro based programs and measuring fixtures. He recalls that:

The industry response ranged from outstanding, right the way through to dismal.

Even at the show a couple of supposed market leaders made it plain they thought that I was wasting their time.

Harry Klein maintains IMS was one of just three suppliers who were very helpful; however, even they thought he was joking about the number of zeros in the tolerance.

But the penny quickly dropped when they realised that, as sawing goes, this RMI process was extremely demanding:

Ultimately they gained the order based on competitive pricing and the confidence we gained from the way that they responded to the project during tendering.

RMI had spent quite a lot of time considering the basic construction of the measuring machine that was needed, given that it was to be operated in a very open environment. A steel structure mated with a granite table was felt to offer the level of robustness necessary. A large machine was favoured to allow fixturing of multiple workpieces and to offer maximum flexibility for development by the existing or any future business.

The 3,000mm × 750mm × 750mm work envelope of the Merlin proved to be ideal and the IMS 32-bit transputer-based continuous motion control important to optimise measuring cycle times on lengthy, repetitive work. The machine was supplied with IMS' Accudat for Windows measuring software, SPC software and a fixed Renishaw TP7 probe with a ceramic tipped cruciform stylus. "We were very pleased with the package IMS supplied," Harry Klein remarks:

The production cell for these components is operated by a team of four people. Two are trained on the machine and others will be eventually, to accommodate the need for a multi-skilled workforce. To smooth out our operations we wanted fixtures that were easily set and simple to access for the appropriate programs, which IMS has provided.

The fixture system locates the parts on their sides and there is sufficient table space for 20 of the small rectangles and eight of the larger sizes. Once the components are in place, the measuring program is accessed by the component reference and the operators can then set to work on other tasks while the Merlin goes through its paces and prints out the resulting data. "Once it has finished its cycle we pack the parts and ship them," says Harry Klein.

The big benefit for RMI comes from making a slick operation out of one that could be very time consuming and laborious. While 100 per cent inspection of the components makes the SPC facility a luxury, its availability is seen to provide a desirable contingency for future requirements.

Average production at Tamworth is 28 parts per day for which the Merlin is in use over a five-hour period. By comparison, Harry Klein and a colleague undertook manual measurement of 60 rectangles during the original cost/benefit assessment that ultimately led to the purchase of the Merlin.

"It took us ten working days," he recalls. "Basic dimensional measurement was straightforward enough but flatness was difficult and the analysis for parallelism and squareness was very laborious," he says.

Manually handling the larger plates, which can weigh up to 70kg, would also be quite dangerous especially with sharp, sawn edges. To overcome this problem, RMI has fitted a vacuum system to the cell. "We quickly realised that a CNC measuring machine was the only viable means of doing the job, compared with manual methods, and the IMS Merlin paid for itself very quickly," Harry Klein insists.

Details from International Metrology Systems Limited, 2 Cochrane Square, Brucefield Industrial Park, Livingston, Scotland EH54 9DR, UK. Tel: +44 (0)1506 462111; Swindon Office: DMIS-CMMCentre, Faraday Road, Dorcan, Swindon, Wiltshire SN3 5HQ, UK. Tel: +44 (0) 1793 619580.