Metal stampings 0.2 - 3 mm

When processing micro-alloyed steels in accordance with DIN EN 10025 in progressive die stamping, we achieve IT classes in accordance with ISO 2768-m on an industrial average, while functional dimensions can be mechanically limited to ±0.02 mm by means of calibration steps. The elastic springback of the material acts as a physical limit which, if not observed, leads to dimensional deviations outside the tolerance range. We safeguard these narrow limits with integrated sensors in the tool to guarantee dimensional accuracy for automated further processing.

During the strip stamping of components made from cold-rolled sheet (DIN EN 10130), the dislocation density in the crystal lattice leads to a significant increase in the yield strength in the forming zones. Although this mechanical effect stabilizes the component, it reduces the residual elongation at break to such an extent that microcracks can occur during subsequent bending operations. To avoid edge cracks in complex geometries, the forming degrees must therefore be kept below the material-specific forming limit curve.

A no-go error is insufficient flatness of the metal stamping components, which induces mechanical stresses when screwed onto the PCB. These stresses lead thermomechanically to the breakage of solder joints (solder joint fatigue) during load changes, which results in the total failure of the electronics. To prevent this, Karl Naumann GmbH uses straightening processes within the validated process chain to maintain flatness within a few hundredths of a millimeter.

Metal stampings with a defined burr are essential, as uncontrolled material protrusion during laser welding leads to unstable weld pools and pores. Mechanically, the burr also prevents a gap-free contact between the joining partners, which drastically reduces the strength of the weld seam. We therefore define a maximum burr height of 10% of the material thickness for critical components in order to guarantee the safety of the welded joint.

As the sheet thickness increases, the shear strength of the material increases, which leads to greater wear on the cutting edges as the punch penetrates. This mechanical abrasion increases the effective cutting gap, which progressively increases the burr formation and leaves the defined edge quality. To safeguard the service life, we use coated carbide tools that delay this effect and stabilize the process capability over high stroke rates.

The shearing process causes severe plastic deformation and residual stresses in the edge zone, which damage the microstructure microscopically. Mechanically, these disturbed areas act as initiators for fatigue cracks under dynamic load, which significantly reduces the service life of fatigue-resistant assemblies. Electrolytic coating or thermal stress relief may be necessary here if the edge load reaches the technical limits of the material.

We use 3D optical measurement to check precision stamped metal parts, as tactile measurements can lead to plastic deformation of the measurement object in the case of delicate structures. Optical evaluation allows the simultaneous recording of complex contours and hole patterns with an accuracy in the single-digit micrometer range. Without this measurement reference, systematic tool errors in large-scale production cannot be detected in good time.

Protection is provided by metal punched parts with reproducible hole positions, which are mechanically forced into position by fixed finder pins in the tool assembly. On the software side, an SPC monitors the statistical distribution of the position dimensions during production in order to detect trends in tool wear at an early stage. A Cpk value below 1.33 leads to an immediate production stop to ensure the conformity of the punched parts.

The submission of a metal stamped part with an initial sample test report, which documents all functional dimensions and material characteristics in accordance with the VDA standard, is mandatory for procurement. This validation ensures that the series production meets the mechanical and chemical specifications of the design. Karl Naumann GmbH also recommends defining component cleanliness in order to rule out consequential damage in automated assembly modules.

Copper alloys or surface-treated steels are primarily used for electrical applications, which are formed into complex conductor structures using precision stamping. Mechanically, these materials must have a high bending capacity, while electrically a minimum contact resistance is achieved through smooth contact surfaces. Materials with low conductivity or a high tendency to oxidize are unsuitable for metal stampings for contact and ground connections, as they lead to thermal failure.

The design is based on the definition of the residual base thickness and the collar shape in order to create a form-fit and gas-tight connection during riveting and clinching. The material is cold extruded mechanically, whereby the strength of the joint depends directly on the ductility of the starting material. Excessive work hardening during pre-punching leads to brittle fracture of the clinch point, which jeopardizes the electrical safety of the assembly.

A critical defect is any remaining flakes or loose burrs on metal stamping components, which are mechanically detached under high voltage and bridge creepage distances. Electrically, this results in an ionization path that leads to arcing and destruction of the system. Mass finishing is therefore mandatory for all live parts in order to guarantee a burr-free surface.

When manufacturing metal stamped parts with multiple perforations, the high punching force causes local residual stresses in the remaining web material. Thermally, these stresses lead to plastic deformation (warpage) during subsequent powder coating or during operation under load. Karl Naumann GmbH optimizes the punching sequence in the subsequent composite in order to homogenize the stress distribution and maintain flatness.

A surface finish such as galvanizing or nickel plating chemically protects the base material against corrosion and mechanically reduces wear at contact points. If this protection is lacking, oxidation leads to increasing contact resistance and thus to overheating of the stamped and bent metal parts. For durable assemblies, the coating thickness must be designed in accordance with DIN standards so that it can withstand the specified number of mating cycles without exposing the base material.

The evaluation is carried out by analyzing the scatter of functional dimensions such as the spring force of contact blades, which is directly dependent on the dimensional accuracy of the bending angles. Mechanically, the process capability correlates with the consistency of the raw material and the tool temperature. Metal stamped parts for SPC and process capability require seamless data acquisition, as unstable processes lead to high failure rates in final assembly.

Residues from punching oils or metallic abrasion have a chemically degrading effect on plastic insulators or lead to electrical leakage currents. The defined component cleanliness is achieved by multi-stage ultrasonic cleaning to ensure compliance with insulation resistances. Metal stamped parts with surface treatment must be cleaned without residue before the coating process in order to guarantee the adhesive strength of the coating.

The technical purchasing department must specify metal stamped parts with a sampling test plan that includes not only the dimensions but also the surface quality and chemical composition (RoHS conformity). Karl Naumann GmbH provides stamped metal parts with a test protocol to ensure integration into complex electronic housings. One exclusion criterion for suppliers is the lack of certified traceability of the primary materials.

Purchasing requires a metal stamped part with a validated process chain, which is documented by a metal stamped part test report for each batch. This includes the chemical analysis of the raw material and the documentation of all critical dimensions. Karl Naumann GmbH ensures that all metal stampings supplied comply with the strict regulatory requirements of the MDR (Medical Device Regulation).

A remaining burr on sheet metal parts punched for ventilation systems generates turbulent flows directly at the edge of the component. Mechanically, this increases the flow resistance and leads to a measurable increase in noise emissions. We therefore use edge processing methods such as brushing or vibratory grinding to provide stamped metal parts with deburred edges that optimize the efficiency of the overall system.

Metal punched components for HVAC applications are often made of galvanized steel or aluminium and additionally passivated to chemically withstand the high humidity. Mechanically, the zinc coating acts as a sacrificial anode to protect the base material from rust formation at the cut edges (edge protection). Without this surface treatment, the constant formation of condensation leads to material fatigue and structural integrity failure.

By punching the holes, the material in the edge of the hole is work-hardened, which massively increases the local hardness. Mechanically, this leads to an increased insertion torque and the risk of screw breakage when using self-tapping screws. To avoid this effect, the hole diameter must be adjusted accordingly for hard materials or the edge rounding must be optimized to limit the assembly force.

The evaluation is based on the long-term stability of the shape and position tolerances at high stroke rates in progressive die stamping. Mechanically, the wear of the cutting punches is monitored by continuously measuring the burr height and the hole geometry. Metal stamped parts for SPC and process capability require automated data acquisition, as manual measurements do not provide the necessary statistical certainty for quantities in the millions.

When punching aluminum, the material's high adhesion tendency often leads to material welding on the punch, which mechanically tears open the edge zone. This effect leads to an increased roughness of the cut edge and reduces the accuracy of fit. Karl Naumann GmbH uses special lubricants and coatings to keep the edge zone smooth and ensure process stability.

They are secured by means of metal punched parts with reproducible hole positions, which are fixed in the tool by means of precise band punching. Mechanically, this allows the automatic assembly machines to grip and position the components accurately. Deviations lead to the assembly line coming to a standstill, which is why Karl Naumann GmbH integrates a 100% inspection of critical features using 3D optical measurement.

For fasteners such as washers or lock washers, metal stampings with high repeat accuracy in the area of the inner diameter and flatness of ±0.05 mm are required. Mechanically, an uneven contact surface leads to uneven preload forces in the screw connection, which jeopardizes its safety. We achieve these accuracies through precision stamping, whereby the technical limit range is defined by the sheet thickness in relation to the hole diameter.

The design takes into account the flow properties of the material in order to create an optimum undercut without material separation during the clinching process. Mechanically, the strength of the joint is determined by the geometry of the stamped and bent part and the residual base thickness. An inaccurate design leads to failure of the joint under shear force, which is why we manufacture metal stampings according to drawings with validated forming parameters.

In order to prevent electrochemical reactions between different metals, stamped metal parts are given a surface treatment such as galvanizing, nickel plating or a zinc flake coating. Chemically, the coating acts as a barrier that prevents the flow of electrons and thus the destruction of the less noble metal. If this protection is missing, the corrosion leads to loosening of the fastening and loss of safety of the assembly.

Spring elements are subject to constant load changes, whereby microcracks in the edge zone due to work hardening during punching massively reduce the fatigue strength. Mechanically, this leads to the spring breaking after a few cycles (fatigue failure). To avoid these failures, Karl Naumann GmbH uses metal stamped parts with a controlled edge zone, in which the cut edges are freed from stress peaks by vibratory grinding or electropolishing.

A critical defect is the use of sheet metal parts punched with rolling defects or cracks in the base material, which are enlarged by the punching shock. Mechanically, the component breaks brittle under load along these defects, which can lead to the collapse of structures. We ensure quality through metal stampings with documented traceability and ultrasonic testing of the primary material.

With thick sheets (up to 3 mm and above), the enormous cutting forces lead to plastic deformation of the edge before the actual shearing process. Mechanically, this results in increased burr formation, which impedes the fit of stamped metal parts for screw connections. We minimize this burr through optimized cutting geometries and regular maintenance cycles of the tools within the validated process chain.

This is ensured by monitoring the dimensional accuracy of thread pull-throughs and openings using SPC in the series process. Mechanically, the stability of the process correlates with the wear resistance of the punches and the consistency of the material hardness. Metal stampings for testing and measuring devices enable rapid validation in order to avoid high scrap costs in large-scale production.

The EMPB is technical proof that all safety features such as hardness, tensile strength and geometry meet the specifications. Mechanically, this guarantees the reliability of the fasteners in use. Without this metal stamped part with initial sample test report, there is an incalculable liability risk for the distributor of the assembly.

Protection is provided by a 100% inspection using metal stampings for optical 3D inspection, which rejects faulty parts before packaging. Mechanically, this allows use in high-speed automatic assembly machines without jamming or misplacement. Karl Naumann GmbH integrates these systems directly into the production line in order to guarantee maximum availability for the customer.

In precision mechanics, we manufacture metal precision stamped parts with tolerances in the range of ±0.002 mm to ensure the low-friction function of gears and levers. Mechanically, the precision stamping process achieves a smooth cut across the entire material thickness, which enables shafts to be mounted directly without reworking. A technical limit here is the surface roughness of the edge, which must be below Ra 0.2 to avoid friction losses.

Metal stampings with surface treatment are often electropolished, passivated or nickel/gold-plated with precious metals in the watch industry. Chemically, this protects against oxidation, while mechanically a flawless appearance and the lowest coefficients of friction are achieved. Scratches or marks on the visible surfaces are an exclusion criterion for high-quality movements, which is why Karl Naumann GmbH uses special tool coatings.

The stamping process causes the structure of small levers and springs to harden locally, which mechanically changes their modulus of elasticity. This cannot be compensated for in the software of rate regulators and leads to rate deviations in the watch. To avoid this effect, metal stampings with a controlled edge zone often have to undergo thermal treatment after stamping in order to homogenize the structure.

A critical fault is insufficient component cleanliness, whereby microscopic metal particles or oil residues block the fine mechanics. Mechanically, such foreign bodies lead to plant downtime or increased wear. We guarantee metal stamped parts with a validated process chain that includes multi-stage cleaning in cleanroom quality to rule out these faults.

Clock plates act as the basis for all moving parts, with the coaxiality of the bearing points mechanically determining the rate behavior. Any deviation in the metal punched parts with a reproducible hole position leads to the gear trains jamming. We ensure this precision by using carbide tools in progressive stamping, which compensate for thermal expansion during mass production.

Even the smallest burrs on metal precision stamped parts prevent the exact superimposition of plates and bridges. Mechanically, burrs lead to misalignment of the arbors, which drastically shortens the service life of the movement. Karl Naumann GmbH relies on precision stamping with a minimal cutting gap in order to physically reduce burr formation to below the perceptible limit.

The evaluation is carried out by analyzing the dimensional stability of the smallest geometric elements under a measuring microscope. Mechanically, the stability correlates with the constant material thickness of the strip steel and the precision of the strip guide. Metal stamped parts for SPC and process capability require 100 % control of the critical features in this industry, as the error tolerance is zero.

When stamping these alloys, there is a strong local deformation of the structure, which leads to uneven results in subsequent engraving processes. Mechanically, the edge zone becomes brittle, which can lead to breakage in the case of fine springs. We optimize edge processing by rounding the edges in the micro range in order to maintain the mechanical integrity of the stamped metal parts according to the drawing.

In the luxury goods industry, proof of material origin and quality is an essential part of brand identity and product liability. Documented traceability guarantees that only certified alloys without impurities have been processed. Karl Naumann GmbH provides this data in full in order to meet the high quality standards of watch manufacturers.

Protection is provided by metal stamping parts for optical 2D inspection, which are integrated into the pick-and-place machine or validated in advance in the QA department. Mechanically, this allows the parts to be transferred to assembly robots without errors. One technical risk here is the electrostatic charging of the smallest parts, which we neutralize in the process chain using appropriate discharge sections.