REINER precision cutting with forming technologyPrecise sheet punching and forming in one work step

Hans-Peter Schmid - Regional Sales Manager
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Hans-Peter Schmid - Regional Sales Manager
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Metal punching permits producing large volumes of flat sheet-metal parts at low unit costs. This is done at high speed, at which large presses with a cutting tool can punch a large number of parts from one sheet at the same time.

To maintain precision of the punched part in this procedure, Swiss Fritz Schiess-Forrer invented the "precision-cutting presses" about 100 years ago.

Three forces are involved in precision cutting, making this technology different from any other punching and cutting method.
Precision cutting results in rectangular cutting surfaces protected against tearing in or off with a maximum smooth cutting share. The part itself remains level and smooth.

In modern practice, precision cutting is combined with forming of the metal piece while pressing. Therefore, the production method is called precision cutting/forming in a double term that has become established across the industry. The special economic efficiency of this production method results from completing three or four work steps in a single pressing process:

• Cutting the flat shape needed from the sheet
• Forming the punched part with bends, insertions, recesses...
• Embossing of grooves, edges, logos, item numbers...
• Smoothing and deburring
(since this post-processing is usually not necessary due to the high-precision cutting)

The relatively elaborate tool production for precision cutting with combined forming technology thereby quickly pays off as the lot size increases.

REINER precision technology – precisely shaped ideas

Interesting facts concerning precision cutting and forming

Competence overview

Dimensions
- 500 x 500 mm opening area of the tool

Part weight
- max. 100 g

Sheet thickness
- 0.5 mm up to max. 4 mm sheet thickness

Materials
- 16MnCr5, CK45, CK75, 1.4306

Machine type
- Schmid precision punching press 250T

Lot sizes
- 1000 pcs. to more than 50,000 pcs.

Advantages of precision cutting
- very good cutting quality and levelness
- economically efficient production of complex functional parts ready for installation

Advantages of REINER
- in-house tool construction / production of precision-punching/bending tools
- many years of experience
- state of the art CNC machining centres for the complete/end processing
- heat and surface processing by reliable partners

Special knowhow
- the focus in on small, technical parts

Why is REINER sheet processing the first choice in precision cutting?

As a manufacturer of long-lived mechanical hand-held and electrical stamps, REINER has always posed special demands to the small precision-parts needed for this. In addition to economic efficiency and flexibility in production, the robustness of every part ensures longevity and high quality of the finished product. REINER contract processing in precision cutting/forming therefore originates in the production process for its own product range. Customers of REINER precision technology can always rely on this grown experience and the high demand for quality of a punched part.

What is precision cutting / fine punching? The essential advantages and disadvantages

Precision cutting combines chip-free separating and concurrent forming of sheets 0.5 to 4 millimetres thick, in metal processing. The production method also called precision punching permits punching of precision parts with cut surfaces without tearing in and tearing off. In contrast to standard punching, precision cutting holds the raw material following the cutting contour using a V-ring. Only in the second step will a stamp with the desired shape cut the metal. This makes serial parts from precision punching very level and permits narrow measurement, form and position tolerances.

The sheet part is often formed and embossed in the same work step.

The requirements to machine technology and tool construction are much higher in precision cutting than in regular cutting. In the press, the sheet is fastened with a counter-stamp and blank holder before and during cutting and a tension is built in the metal sheet when shearing. This prevents tearing off and breaking surfaces at the cuts of the punched part, while at the same time increasing the forming capacity of the material. These tear-off-free cutting surfaces usually render post-processing unnecessary and leave the punched part immediately usable for installation.

How does precision cutting and punching work as a forming technology for serial parts?

It was a logical step of development to apply further forming steps to the already-cut and fastened part in the press – in the same process. The forming technology therefore integrates desired operations such as bending, insertions, offset, recesses and embossings. This replaces elaborate post-processing.

Which precision cutting applications and examples are there?

The punched parts from REINER precision technology are used in all applications of precision mechanics: Medicine, hand/electrical tools, aviation and aerospace, arms technology, sensors, closing technology.

Which materials are used for the sheets in precision punching?

The metals used most frequently for precision cutting at REINER include case hardening steel 16MnCr5, Q&T steel CK45, cold-rolled spring strip steel CK75 and non-corrosive austenitic steel.

Case hardening steel 16MnCr5 (Euro norm: EC80)

Case hardening steels are mostly used in the area of engineering for parts subject to higher stress and higher core strength, e.g. for measuring tools, joints and gears. Case hardening steel has a hard edge layer and a resistant core thanks to case-hardening.

Q&T steel C45E (formerly: CK45 / DIN 1.1191)

This steel is suitable for punched parts subject to dynamic stress in machine and tool construction since it is very strong and tension-resilient. It is tempered by transformation hardening. The carbon share is between 0.2 and 0.65% and the material properties are controlled specifically by alloys with chrome, manganese, nickel and molybdenum.

Cold-rolled spring strip steel CK75 (stainless steel DIN 1.1248)

This steel is used for production of flat springs, form springs or leaf springs.

Non-corrosive austenitic steel (DIN 1.4306)

Austenitic, acid-resilient Cr-Ni-steel is predestined for use in environments with water, steam, food acids, etc. It can be found in systems from the food, pharmaceuticals and cosmetics industry, medicine and façade technology. It has an extremely low carbon content, which leads to increased resilience to intercrystalline corrosion while hardness, strength and maximum elongation are particularly low in the quenched condition. The steel polishes very well and can be cold-formed well.

What qualifies REINER punching for the sheet-metal part production?

Daily cooperation with our customers is characterised by targeted development of innovative, application-specific solutions. Our engineers get their experience primarily from the company's own production process for REINER products "Made in Germany" – and of course from projects implemented for our demanding customers. The designs and forming technology adjusted to precision cutting are developed by employees who are aware of the entire production process even when producing a single small sheet part. This ensures an economically optimal production even on complex forming technology.

REINER has acquired comprehensive experience in controlling all influences for successful use of precision/forming technology in more than 20 years and millions of produced parts. Our in-house tool construction and tool design guarantee product precision. Our employees have profound knowledge of the forming properties of every metal used.

REINER precision technology – precisely shaped ideas