Workpiece Clamping – The Pre-Stamping Advantage!

Best accessibility and highest holding forces!

To find the perfect clamping fixture for all requirements is relatively difficult, if not impossible. In workpiece clamping compromises have to be made often by the user. Holding power, accessibility, handling, repeatability and material deformation are parameters that play a deciding role and depend on each other.

Lang Technik GmbH in Holzmaden presents with Form Closure technology a unique approach which, for the last decade has been an approved method and has convinced thousands of customers.

Form Closure technology, also known as pre-stamping, is a patented technology, by where the workpiece to be clamped is indented with a defined contour with high stamping power before it is clamped in the clamping fixture, offline or outside of the machine tool.

Pre-stamping is a controversial issue broached among many experts with some companies challenging the cost versus use. That's why we would like to combine facts and data to help you decide if, and from what point on will the use of pre-stamping be cost effective in your manufacturing processes.

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When does it make sense to pre-stamp workpieces?

Clamping processes that require a high holding power but risk the danger of workpiece deformation can be mastered with assurance with pre-stamping. For 5-axis machining, where optimal accessibility needs to be reached, pre-stamping technology is a must.

With pre-stamping as a factor, the LANG 5-axis vise can be constructed lightweight and compact .The light construction is an advantage if clamping fixtures need to be set up and torn down often.

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How does the investment in pre-stamping technology influence manufacturing?

On the surface it looks as though pre-stamping of the workpieces is adding an additional production step. With a maximum timeframe of 5 seconds per workpiece, a beneficial return on investment is quickly realized.

Pre-stamping affects multiple factors including process reliability and profitability.

The excellent accessibility of the 5- axis vise allows the use of shorter tools. The vibration reduction through shorter tools provides longer tool life and a high quality, workpiece surface finish. The results are shorter manufacturing times due to higher cutting data.

The pre-stamping process applies a 0.25mm indent to the raw material, comparably shaped to a pyramid. Thanks to stamping technology a repeatability of 0.01mm can be reached through these defined indents.

The high pressure applied while pre-stamping relieves the function of the LANG vise, now reduced to holding the workpieces through the form closure technology with a relatively low clamping force of 2 tons maximum (depending on material). Deformation of the workpiece in the vise is nearly impossible and the holding teeth on the vise jaws are not subjected to the usual wear and tear guaranteeing the user a constant and even clamping quality with pre-stamping.

Through the external pre-stamping of the workpiece with up to 20 tons of hydraulic pressure it is possible to stamp raw material with a tensile strength of 1500N/mm2 continuously with a defined form closure indent, resulting in excellent holding power. The clamping need of the workpiece is less than 3.5mm and leads to lower material removal on the finishing side.

Clamping with form-closure through pre-stamping makes the clamping of "oversized" workpieces possible; even at only 3mm clamping depth.Depending on material characteristics and milling parameters workpieces can be held securly even if their size exceeds the actual jaw width by a factor of 2 or even 3.

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Additional costs for pre-stamping?

Customers often just look at the hard facts, namely the actual invoicing of fixed costs. With stamping technology it is worth looking below the surface at variable costs. The initial purchase price might look expensive to the buyer as an additional item to buy, but buying the LANG stamping/clamping system needs to be looked at as a package. The compact design of our LANG 5-axis vises are only possible with the pre-stamping technology, which when compared to similar vises are more cost effective. Additional costs for additional vises or replacement parts are also reduced to the minimum, taking into consideration the initial cost of the Lang pre-stamping/vise package are almost the same, not to mention the production technology benefits and the high economic efficiency.

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How do vises work without pre-stamping?

Along with traditional flat jaws most of the vise manufacturers also offer grip or serrated jaws. Without stamping technology the vise has two functions:

1.    Setting the stamping contour
2.    Holding of the workpiece within the form-fit

As mentioned previously, conventional vises only have a holding pressure of about 4-6 tons maximum. A large vise body is necessary to create this power. This reduces the usable machine tool space and also negatively affects the accessibility to the workpiece, combined with a high weight this also affects handling. High holding pressure constantly affecting the workpiece can lead to deformation while applying and relieving pressure. If a conventional vise is built compact, the loss of holding power is noticeable.

Without a doubt, the advantages of pre-stamping in 5-axis machining include:

  • Consistent clamping quality
  • Best accessibility
  • Shorter tools
  • Higher cut amounts
  • Shorter machining times
  • High surface finish quality
  • Light handling weight due to compact design of the vise
  • More machining space available
  • Enormous holding power due to Form Closure
See for yourself and experience our products in your company. We would be happy to visit your location and work together to see the possibilities to get more out of your manufacturing.

Find out more about pre-stamping and the Makro-Grip 5-Axis Vises in the stamping technology and workholding categories.

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