Productivity and flexibility are characteristics that every manufacturing company wants its production equipment to have. A key concept here is shorter lead times – easy to say but not so easy to achieve. It takes expertise, energy, innovative thinking and a certain amount of courage. If you succeed in becoming so flexible that you can in principle produce a single part as economically as a run of 50 or 500, you’ll have taken a big step up the ladder of competition.
Bengt-Göran Nilsson: “It came down to a choice between automation or losing the race to the low-wage countries.”
AB Kinnex Mekaniska of Götene, Sweden, has taken that step. Bengt-Göran Nilsson, Marketing Manger at Kinnex, says – “Part of my job is to pick up signals from our customers. After all, the market is constantly changing. A few years ago, we realised that we weren’t focusing on what our customers wanted. We were in a rut. We made what we had always made – what we thought we were good at.”
“Our customers, headed by Tetra Pak, were beginning to ask for short runs of complex products, and we were expected to take responsibility for everything. And to stay in the game we were forced to meet our customers’ requirements – simply to supply what customers wanted!”
“This means facing up to the question: Shall we make 30 parts, deliver two and put the rest on the shelf? And the next question: Will there be a change to the drawing later on, meaning that the parts we’ve already made are more or less useless?”
“In addition, our internal OEE measurements showed that our spindle times were around 50 percent. If this were a Formula 1 race, our cars would be in the pits half the time! That’s not how to win races. So it was time for a re-think.”
The company Board drew up a five-year plan for technology investment. New production technology to increase flexibility and free up machine time, together with competence development for the employees.
Short runs or one-piece production mean frequent retooling and lots of downtime, as confirmed by the OEE measurements. To put it bluntly: an hour’s spindle time needed an hours’ setting-up time. Unsustainable in the long term, of course!
So serious steps were taken to reduce setting-up times. Standardised clamping of the workpiece in a vice was introduced. Because this ‘embosses’ the workpiece, it requires very little material intervention. The vice is mounted on a System 3R Delphin pallet which positions the workpiece on the machine table to within a few microns.
Typical Kinnex jobs – to the left a hydraulics block for a mobile crane.
All preparations are done away from the machines, while the machines are continuing to run. When a job is complete, the part/vice/pallet package is lifted out and the new ‘package’ is lifted in. Within a minute or so the spindle can start turning again.
Then came the crucial step – an automatic production cell.
Kinnex installed a Deckel Maho DMU 80P with a 300-position tool magazine. The machine is served by a WorkMaster which handles the changing in and out of the pallets with their workpieces. Manned or unmanned. Day or night. Weekdays or weekends. All that has to be done is to keep the magazine loaded with workpieces.
The heart of the automatic cell is the pallets and the robot from System 3R.
Operator David Persson says: “My work has become more interesting and meaningful. Most of the production planning work has been moved out to the cell. Each pallet has a code carrier with a unique identity, which is scanned when the pallet is loaded into the cell. The cell already holds all the programs for the part on the pallet. If an urgent job comes in, it’s simply a matter of preparing the pallet, loading it, changing the running order and pressing GO.”
Bengt-Göran Nilsson concludes: “The entire cell cost about 650 000 euros, but we’ll soon earn that back. We’ve doubled the spindle hours and significantly reduced lead times, so that now we can deliver just what the customers want. Without increasing stock. Even single parts if the need arises – and we can do it fast!”
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Layout drawings:
WorkMaster & DMU 80P
WorkMaster & DMU 50eVolution Linear
Related links:
WorkMaster
Delphin