Oddform route through A to Z of control
27 August 2008
A huge investment in an oddform line is delivering a massive difference in throughput. Tim Fryer went to visit Danfoss Randall’s factory to see the line in action.
It is easy to imagine that electronics manufacturing has become ‘sanitised’, in as much as the shift from OEM to EMS has meant that so many manufacturing sites become carbon copies of each other. Serried ranks of SMT lines followed by manual assembly, test and box build. In a global sense these factories have to replicate each other as they are often moved from one low cost geographical location to the next.
If you want to see variations in the set up the place to go is an OEM. Usually the manufacturing environment has evolved with the end product’s requirements – making the most of the existing production equipment while investing in the new. The result is the more ‘quirky’ factory set-up, tailored to optimise the production of a particular portfolio of products.
Danfoss Randall Ltd is such a factory. Based in Bedford the company has a rich history in heating controls – Randall Electronics Ltd development of electro-mechanical time controls for central heating in the 60s and Danfoss’ invention of the radiator thermostat in 1943 among them. Danfoss acquired Randall Electronics Ltd in 1991 and merged it into its Heating Division and now the site is the manufacturing facility for the company’s extensive range of heating control products. While the majority of products are electronic heating controllers for domestic use, there is still demand, particularly from local councils, for electro-mechanical controllers, as a direct replacement for existing electro-mechanical controllers.
Manufacturing has evolved in cells, each responsible for the assembly of a number of the 30 or so main product families. All of the cells are served by a common automated board assembly facility – namely a surface mount stage followed by an odd-form assembly process. It is in the latter area that Danfoss Randall has recently invested around Euro 1.5 million in new equipment.
The surface mount area consists of two identical lines, each comprising a SMD placement machine, a reflow oven and then an inline optical inspection machine. While ageing gracefully, this line is more than capable of keeping up with both the speed and technology requirements. Boards are typically single sided and the smallest component is 0402.
However, the company had historically faced a challenge after initial surface mount assembly, where the hand placement and soldering of the odd-form components was proving to be a bottleneck. As a consequence, the Danfoss Randall invested in a PMJ oddform/soldering line over ten years ago. The line consisted of one pin cell, two oddform cells (fitted with intelligent feeders) and two selective soldering cells.
This oddform line was placed in a separate room, along with the SMT lines, to form an automated assembly area. Industrial Engineering Manager Kevin Hannah explained the reasons for separating the automatic equipment: "We had the room originally to save the solder paste. We could control the environment and so get the conditions just right. But paste has longer stencil life now and we use it up quicker anyway, so we don’t really need to keep the automatic lines in the extra room anymore. We have been extending it year on year though."
The most recent expansion came last year. The original PMJ line had reached capacity and it was clear that further investment needed to be made. While the SMT lines were still feeding boards at the required rate, the oddform line was lagging behind. Kevin and his team decided that it was time to replace the old oddform line with a new solution from Cencorp – the metamorphosis of PMJ – as the team remained impressed with their existing oddform solution.
The new solution cost around a million pounds and consists of eight cells – three oddform, one pinning cell and four soldering cells. All cells are customised versions of the Cencorp 1000OF system, tailored to meet Danfoss Randall’s needs. The cost and size of the line makes the company the largest user of the Cencorp machines in the UK. The new line has been housed in the extended automation room at the expense of the old line, which has been moved out into the main assembly area. Given the number of new products being introduced and a generally strong order book, the old line is still an important contributor to production capacity.
The new line has added substantially to throughput and can churn out a board every few seconds. This huge improvement in throughput (3 times faster) compared to the old PMJ line reflects the progress that has been made over the intervening years in these cells.
Now in their 4th generation, the cells productivity is not just based around basic pick and place speed, but also on the automatic tooling options and intelligent feeders which make product changeovers both immediate and fully automatic (if the right component set is on the machine). The oddform cells also offer novel active servo controlled clinching, which senses if the component lead has gone through the board before performing the crimping function. There is a similar facility on the selective soldering cells, where an encoder on the wire feed is used to ensure that exactly the right amount of wire is used for each joint.
The pinning cell is a true piece of customisation as the pins (and some contact blades) need to be riveted into the board – a combination of precision and force that was unavailable on other machines. This cell has been fitted with dual heads to increase throughput. Each head is controlled by its own robot, so different types of board can be assembled concurrently.
The overall effect of having an odd-form capacity that, in terms of number of machines, outstrips the surface mount offering does not fit the normal model for an electronics manufacturing site. As stated at the beginning of this article, this is the sort of non-conformity that has evolved out of necessity as Danfoss Randall has developed the ideal manufacturing solution to meet its needs.
There are other pressures at work that are standardising certain aspects of the manufacturing environment. Danfoss has rolled out its Danfoss Productivity Program (DPP) throughout all of its sites around the world, irrespective of what each site is manufacturing and how. This staggered program has been in operation for two years and the latest initiative is to introduce a Kanban – a project that is currently underway at the Bedford site. Kevin commented: "There is no doubt that the lean manufacturing in DPP has really worked for us, but it has been a big change. The most obvious impact has been reduced WIP on the work floor.
“Danfoss Randall is constantly developing new products using new technology in order to fulfil the increasing customer needs regarding better and more intelligent heating controls and with our new Cencorp line we have the capacity in place to manufacture them as well!”
Danfoss Randall Ltd
Tel: 0845 1217400
www.danfoss-randall.co.uk
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