They do not only ensure that manufacturing quality increases and dies are clamped safely, but also that this change takes place very quickly. Rapid die change allows companies to manufacture even low numbers more efficiently and in a shorter time. As a frequent result, storage may be reduced. The consequence of this again is a reduced demand of space and capital.
On the other side, rapid die change provides for longer machine operation times and hence additional capacities to be used for new orders. Since they usually are easy to handle, they can even be operated by non-experts.
Die change standardization and simplification
Some die clamping and changing systems can also be used flexibly so that the number of required clamping elements may be reduced. In addition, they can frequently also contribute to standardize, simplify and automate die changing processes. For this purpose, the functions of the clamping elements can be controlled by central machine control units within integrated production processes. Monitoring elements - in particular for pressure and positions - supply controls with feedbacks at the same time and consequently contribute to achieving high process reliability and productivity.
The high-end solution, "magnetic technology" even allows for clamping all steel dies of any geometrical shape, size and mass an largely do without other clamping elements.
Clamping systems also offer advantages with regard to manufacturing quality and the lifetime of dies. The even and low-distortion clamping process, the always possible precise repeatability of this step, and the selection of optimum clamping positions contribute to a constantly high production quality. This simultaneously reduces wear on the die.
Before making a decision on the eligible clamping technology, the purpose of use should be clarified: Is the primary aim to simplify operation, to lower the number of clamping elements or to reduce die wear? Or is it primarily about increasing machine productivity and product quality?
Andreas Reich, Product Division Head of Quick Die-Clamping Technology of ROEMHELD at Hilchenbach, emphasizes that affordable standard components are available for a large number of tasks; these may be composed of modular programs. "Even specially customized solutions for particular requirements are available on the short term and at moderate cost", explains the clamping technology specialist.
Investments pay off soon
He vehemently refuses to the sometimes heard objection that clamping technology was expensive. "A simple estimate calculation already shows that investments will amortize in a very short period in most cases."
His example: Given 250 working days per year and a single die change per shift, 500 dies are changed every year in two-shift operation. With manual clamping screws, the changing time for each die change amounts to around 25 to 30 minutes. Considering the appropriate hourly rate of the machine, die changing cost amount to Euro 5,000 per month, which is Euro 60,000 per year. In contrast, according to his calculation, the comparable die changing cost when hydraulic quick clamping systems such as hollow-piston cylinders, clamping strips and hydraulic power units are used, amount to only Euro 15,000 per year. They finish a die change in only six minutes. Taking investment cost of Euro 8,000 to 12,000 into account, this results in a total of approximately Euro 27,000. Consequently the saving in the first year already is Euro 33,000. Reich's conclusion: "The investment will have amortized in a few months only."
This does not even take into account that the gained machine operation times extend production times and hence generates further yield by higher capacities. The Product Division Head calculates again: "Due to the die change in six minutes, daily die changing times are reduced by well over half an hour." With 250 working days, this results in 125 hours more machine operating time to be used for additional orders.
Mechanically, hydraulically or magnetically?
But which clamping system is to be used for which application? The expert explains: "I recommend simple hydro-mechanical clamping nuts - optionally with clamping force indication - compact claws and mechanical plug-in clamps if the clamping edge heights and widths of dies are uniform and clamping times of several minutes per clamping point are acceptable."
In comparison to these, hydraulic clamping elements such as hollow-piston, plug-in, angle and wedge clamps significantly reduce the clamping and releasing time to between eight and twenty seconds. The die is fixed on all clamping positions simultaneously and evenly fixed at the touch of a button and hence without any effort. "Hydraulic clamping is faster and has a positive effect on process reliability and production quality", Reich reports. "In addition, the clamping force may be monitored and controlled, and the changing process may be automated.
Only electro-permanently magnetic clamping plates positioning and clamping dies in less than three seconds are even faster. The magnetic clamping plates are manufactured according to the customer’s specifications and are particularly useful when dies must be changed frequently. They are also preferable, if many differently dimensioned dies are used. If they are made of steel, they may be clamped without exception without the need to standardize clamping edge heights and die base plates. For newcomers to this technology, ROEMHELD has introduced the "Clamp & Go" product line of magnetic clamping plates available at attractive prices. The series comprises affordable magnetic clamping plates standardized in size and design and intended for a broad circle of users. As most other clamping elements, they may easily be retrofitted to the majority of machines.
Andreas Reich is Head of Quick Die-Clamping Technology for ROEMHELD
at Hilchenbach, phone: 02733 28 11 62, email: email@example.com