With 22 DMG Mori machines, rising to 23 when the next DMG Mori NMV3000 DCG with 32 pallets is delivered, Martin-Baker, known worldwide for its ejector seats, is a major customer for DMG Mori.

Martin-Baker has been a leader in the design and manufacture of ejection and crashworthy seats for over 70 years. During that time, its seats have saved over 7,500 lives and the company has been honoured to receive 11 Queen’s Awards. Its latest designs offer unprecedented life-saving capabilities and there are over 17,000 of its seats currently in service.

The company supplies ejection seats for 56 different aircraft and spare parts for existing seats still in service ranging back to the 1970s. In addition, special seat requirements vary for the same aircraft between more than 90 air forces it supplies depending on factors such as the terrain it is to operate over and the aircraft seating configuration.

The complexity and variation of the seats results in a large number of specialised components. Rupert Hanak, head of production engineering at Martin-Baker, explains the difficulties the company needed to overcome for efficient production: “We have thousands of different components and batch sizes are often 5 to 15 parts. The length of each production run is too short for us to develop faster cycle times, so the key objectives are an extremely quick change over time between different parts and, process reliability so that we know that parts will be right first time. We are consistently achieving over 80% OEE 24/7 with the technology we are using.”

At the heart of Martin-Baker’s production is a manufacturing cell consisting of four DMG Mori NHX4000 2nd Generation horizontal machining centres, each with 240 tools, connected together with a DMG MORI LPP (Linear Pallet Pool). This system has 70 pallets and supports 500 completely different active parts. A VIO tool presetter services the machines and links them, to download the tool setting data. Martin-Baker has a core of around 200 standard tools, which the CNC programmers have to work within, on each of the NHX4000 2nd Generation machines.

The production schedule is controlled from Martin-Baker’s SAP system, which displays a list of the next four weeks’ worth of jobs to be completed on a terminal on the LPP. The engineers can then use their experience to select the order in which they should be run, picking long running safe parts for the unmanned night shift and more challenging work for the day shifts with the aim of maximising output for the available hours.

Hanak adds: “We use Mori Messenger in the office to monitor machine activity and gather metrics. The system shows the run rate of the machines and displays alarms. I can then drill down into the data to find the problem, which could just be machine loading and work availability or tooling problems such as swarf wrapped around the cutter. We can then take action based on the data, for example, editing the CNC program. Essentially, all our decisions are data driven.”

Within the software solution, SAP knows the workholding requirements of each job, the machining time and the tooling. Linked to the LPP system the correct pallet and fixture is then presented to the engineer for loading. Extra software supplied by DMG Mori detects broken tools and tool ‘out of life’ situations, ensuring that a job which requires the faulty tool is not loaded to the machine and automatically cutting another job from the work list, while the problem is remedied. The system also has the ability to recognise sub locations on a pallet. DMG Mori has added extra buttons on the control system which make it possible to skip over these sub locations if no material has been loaded. Hanak says: “We have had a considerable amount of applications support from DMG Mori to tailor the systems to our requirements and we have a DMG Mori engineer on site permanently to ensure the smooth running of our machines and to fully maintain them. We apply SMED (single-minute exchange of dies) principles to all our machines, and DMG Mori has been a very good partner in helping us get to the level we have achieved.”

The NMV3000 DCG 32 pallet machines enable multiple operations to be combined on one machine using their 5-axis capabilities. One of the machines is used to produce a rocket motor end cap family of parts, running one manned shift and 16 hours unmanned, yet still achieving 80% OEE. Hanak adds: “With 5-axis and turning capability on one machine we can go from raw material to finished part in one step. We used to subcontract some of the parts we put on the NMV3000 DCG. By making them in-house we now have more control over security of supply. Additionally, completing each job on one machine eliminates the complexity and chances of something going wrong associated with multiple operations.”

Martin-Baker has a range of NTX, NT and NL turning centres. Rationalisation of bar sizes minimises changeover times between different parts and, even when the bar needs changing, this is achieved within 15 minutes. A CAPTO interface on tools and a tool management system eliminates wasted time for sister tooling replacement and reloading of offsets. Innovations added by DMG Mori include special part conveyers to safely unload critical components which cannot have any surface imperfections. One of the NL machines is even used for machining rocket fuel and has been heavily modified to provide fire damping and remote operation from a safe room.

Hanak concludes: “DMG Mori is a good and responsive partner. The machines it offers are highly flexible and the service is second to none. We have a continuous training program which is motivating for our employees and helps us to embed our vision and work practices throughout the factory. Combining these advantages with planned maintenance, a service schedule and a DMG Mori engineer on site has enabled us to achieve the high OEE levels we have come to expect.”

www.dmgmori.com