Lean goes with rapid

Tom Shelley reports on thinking that combines lean design, rapid prototyping and fast to market



Designing ‘lean’ can slash time to market by 75%, with added benefits of lower cost and higher product quality.
These were the main conclusions of a seminar organised by Kent Business Link and held at Greenwich University in Chatham.
Doing it lean means doing it efficiently and without wasted time or effort. David Lanckmans, sample manufacturing manager at Delphi Diesel Systems in Gillingham, Kent explained how his company had improved its design and production engineering processes to slash delivery time of sample diesel injection pumps from 18 weeks (in 2002) to as few as five weeks today. This is despite increasingly strenuous specification demands, such as requests to manufacture to tolerances of 0.1 microns. The pumps contain 100 to 150 components.
“It is vital to win the business,” he says. “But if the pumps fail to meet customer requirements, there is no second chance. The priority is therefore quality and delivery on time.”
The design to manufacture process starts with 3D designing in SolidWorks. Some parts are rapid prototyped using the Fused Deposition Modelling facility at the University of Greenwich in Chatham. For Delphi, ‘rapid prototyping’ means fast production of finished metal pumps by machining steel and aluminium alloy.
“It would be nice if designs were right first time, but it must be possible to make changes to the design within the delivery date,” says Lanckmans.
Plastic rapid prototypes were made of several components: the complex pump front plate – which is an aluminium casting in production; tools to make investment casting moulds; and the cast iron cover. Raj Bhatti, a principal lecturer at Greenwich who runs the rapid prototyping facility, said that the plastic rapid prototypes can highlight features that are not apparent from the CAD model, such as visualisation of where parting lines should be and, in one case, an offset undercut.
CAM instructions are prepared using Virtual Gibbs CAM, post processing and verification of tool paths in Vericut. Machining is supervised by Seiki Systems Program Management Machine Monitoring software.
Much of the reduction in lead time, however, was not obtained using clever software but by changing the management process following the phrase Stan (“Stop and Take Action Now”). The process began back in 2000 with the appointment of an ex Toyota lean guru to lead a critical and detailed analysis of flow in all areas. This generated a 40-foot-long wall chart. Action planning was undertaken using lean tools that included: MSD (manufacturing system design), VSM (value stream mapping), Future States and Pareto Analysis.
Lanckmans emphasised that none of this implied downsizing. “Our goal was the empowerment of individuals so we could get more business,” he says. “We needed to nurture the skills we had and did not wish to lose them.”
Members of the project team, including project managers, design and development engineers and production staff were re-sited in the same centralised location. There are now daily start up reviews, which set priorities for the day. Weekly shortage reviews track internal and external components promised, design status and current customer needs. Twice-weekly production reviews agree priorities and plan the week, while monthly meetings brief everyone regarding current performance and future activities.
The target for 2007 is complete sample manufacture in four weeks instead of five. Greenwich University lecturer Samantha Berkhauer pointed out: “Non-value added operations typically account for 95% of manufacturing lead time” and advised: “Do not assume information flow follows material flow.”
Rapid prototyping it is at Delphi, although Dr Bhatti, is not so sure that the layer by layer building up of plastic products should always be called by that term, even though it often undoubtedly assists such a process.
“You should be able to get a product out in 72 hours or it isn’t rapid,” he says.
His facility uses an FDM machine to produce ABS models that can, in many cases, be used. ABS can be painted, machined, drilled, tapped and have threads cut in it. The base material can be produced in any colour, although Dr Bhatti says that yellow is best for showing up imperfections and roughness. If the model is to be used as a component, certain mechanical matters need to be considered.
“Rapid prototyped models are like balsa wood – you can get weakness along the grain but strength across it,” he said. “There is also a problem with fine screw threads that are liable to strip.”
While reluctant to be drawn on precise costs, Dr Bhatti revealed: “The most Delphi has had to pay is £250 for a fairly complex piece of housing.”
The university can produce models up to 200 x 200 x 300mm. Resolution is 0.25mm. Input is preferably in the form of a 3D CAD file, (Drawings or DXF files that can be converted into STL format). The team will accept paper sketches but makes a charge for turning them into CAD models.


GibbsCAM
Business Link Kent

Low cost seminars
The seminar at Greenwich University was organised by Business Link Kent. These particular Breakfast Club meetings take place four times a year. Business Links organise meetings to assist business efficiency nationwide. They are generally free or modestly priced. This event was aimed at the needs of Kent, but included attendees from London and Surrey. Free advice from Business Links is also available over the telephone.

Author
Tom Shelley

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