The degree of drawing that can be achieved when using deep-drawing materials such as DIN EN 10130 (DC04) is mechanically determined by the ratio of the platinum diameter to the drawing die diameter, whereby we usually aim for limit drawing ratios of βmax ≈2.0 to 2.2 in a single-stage process. Physically, exceeding this limit leads to the tensile strength in the base area of the component being exceeded. Too high a degree of forming results in an uncontrolled material flow and provokes a technical exclusion criterion due to bottom tearing, which jeopardizes the structural integrity of the drawn parts.

A higher sheet thickness stabilizes the forming process mechanically, as it increases the resistance to wrinkling in the flange area and enables the use of lower specific hold-down forces. Physically, a higher s0/d0 ratio improves the stability behavior of the blank under tangential compressive stresses. In contrast to extremely thin sheets, an optimized thickness reduces the risk of instability, but the plastic ductility of the material limits the maximum drawing depth before cracking occurs.

Multi-stage deep drawing is absolutely essential if the required total height of the component exceeds the limit drawing ratio of a single operation or if complex drawn parts with steps and secondary forming elements have to be realized. The diameter of the workpiece is mechanically reduced in each subsequent stage, while the material flows plastically over the radii of the drawing die. Without this step-by-step forming, the local work hardening would exhaust the deformation reserve of the steel before reaching the final geometry, leading to total failure of the deep-drawn parts.

Wrinkling occurs mechanically due to insufficient hold-down stresses, which causes the blank to deflect in the draw-in area under tangential pressure, while cracking is induced by excessive friction or a drawing radius that is too small. Physically, a radius that is too small leads to a local stress concentration that locally exceeds the material's yield strength. In large-scale production, these defects lead to unstable component properties, which is why Karl Naumann GmbH precisely calibrates the parameters in order to eliminate rejects in drawn parts to prevent wrinkling.

The drawing radius on the die mechanically influences the bending and rebending work as well as the radial tensile stress, whereby a radius of around 6 to 10×s (sheet thickness s) often represents the optimum. Physically, a radius that is too large leads to premature wrinkling in the free area, while a radius that is too small stretches the material excessively and weakens the edge zone. An incorrect radius design results in insufficient fatigue strength, which represents a safety risk for fatigue-resistant assemblies in the area of unit bearings.

We ensure controlled wall thickness distribution through targeted control of the drawing gap ratio and lubricant viscosity in order to limit mechanical thinning in the transition radii to a maximum of 15 to 20%. Physically, homogeneous friction prevents local constrictions due to uniform material flow from the flange. Exceeding this thinning limit leads to a weakening of the cross-section, which represents a critical risk of failure for drawn parts with a defined wall thickness in the deformation zone.

For sheet metal drawn parts in the visible area, a maximum roughness (e.g. Ra less than 1.6 µm) applies in order to mechanically ensure a homogeneous appearance without an "orange peel effect" after the painting process. Physically, the surface topography must be such that it reliably transports the drawing medium into the forming zone without provoking local metallic contacts. Poor surface quality leads to visible streaks and is a primary exclusion criterion for metal drawn parts in the automotive industry.

We use image-processing 3D optical measurement and tactile coordinate measuring technology to verify geometric features in the micrometer range in order to ensure the high dimensional accuracy of the drawn parts. Mechanically, this ensures the dimensional accuracy of drawn parts with functional geometry and their fit in component assembly. Karl Naumann GmbH documents these results for each batch, as a deviation in the reproducible deep-drawing position would have a negative impact on the chassis geometry.

Process capability is assessed by statistically evaluating function-critical dimensions using SPC, whereby we require a Cpk value of greater than 1.33 as a technical standard. The stability of the blank holder forces and the material batch is monitored mechanically in order to detect creeping changes in the forming behavior using software. A drop in the capability parameters indicates unstable friction conditions, which unacceptably reduces the quality of the drawn parts in series production.

The initial sample inspection mechanically documents that the tool design and the validated process chain are capable of reliably reproducing the required geometry under series production conditions. Physically, this report confirms that material parameters such as the r and n values (anisotropy and hardening) have been correctly taken into account for the drawn parts according to the drawing. Without a positive drawn part with initial sample verification, there is a risk of assembly problems for the purchasing department, which could jeopardize on-time production.

For EMC shielding, we primarily use soft magnetic materials or tin-plated deep-drawing sheets in accordance with DIN EN 10130, which have excellent mechanical flow properties for precision drawn parts. Physically, the high ductility of these steels enables the drawing of complex drawn parts with functional geometry without intermediate annealing operations. Materials with insufficient magnetic permeability are not suitable for this application as they cannot guarantee the electrical shielding attenuation of the housing integration.

We limit distortion and ovality by using multi-stage tools with integrated calibration stages, which mechanically homogenize the residual stresses in the component. Physically, the elastic springback is minimized by controlled repressing in the base and wall area. Inadmissible ovality in drawn parts with tight tolerances leads to the rotor jamming, which destroys the functionality of the precision drawn parts in the drive technology area.

Cracking in drawn parts with pull-throughs is usually caused mechanically by exceeding the forming limit during collar drawing if the edge of the pilot hole is too rough or has microcracks. Physically, the tangential elongation at the collar edge leads to stress peaks that exceed the material strength. Karl Naumann GmbH uses precision-ground pre-punching dies to ensure a stable edge zone and prevent the metal drawing parts from failing.

Progressive drawing is technically superior when drawn parts in large series need to be combined with additional punching or bending operations in order to produce ready-to-install components for component assembly. The component is mechanically guided through the stations on the carrier strip, which guarantees high repeat accuracy of the positional relationship between the drawing and punching features. Simple cup drawing, on the other hand, is limited to rotationally symmetrical basic bodies without complex edge geometries.

Controlled wall thickness distribution is ensured by precisely adjusting the hold-down pressure bolts to mechanically prevent asymmetrical material flow. Physically, this ensures a uniform material thickness over the entire circumference of the drawn parts with functional geometry. An uneven wall leads to local distortion under thermal stress in the enclosure and impairs the accuracy of fit of the enclosure components.

We use 3D optical measurement to quickly record flange widths and base thicknesses in order to mechanically ensure that the drawn parts with flanges fit flush into the system environment. Physically, this non-contact method enables the measurement of thin-walled drawn parts without deforming them through probing forces. Any deviation from the reproducible geometry is recorded in the test report to document the quality in electrical engineering.

Process capability is crucial, as the slightest variations in geometry can mechanically cause the parts to jam in vibratory conveyors or automated feed rail systems. Physically, the center of gravity and symmetry of the drawn parts must be within very narrow limits to ensure trouble-free placement. An unstable process drastically increases downtimes in component assembly, resulting in high downtime costs.

The relevant standards are DIN EN 10130 for cold-rolled flat products and ISO 2768 for general tolerances, although tighter factory standards often apply to precision drawn parts. Mechanically, these standards define the permissible deviations in thickness and shape, while DIN EN 10025 is used for load-bearing structures. Failure to comply with these standards leads to a loss of traceability and jeopardizes certification for appliance manufacturing.

The design is based on an optimization of the edge zone and the controlled wall thickness distribution in order to achieve a high mechanical contact pressure with low material fatigue at the same time. Physically, the work hardening must be controlled in such a way that the electrical conductivity does not drop unacceptably while the mechanical rigidity for fatigue-resistant assemblies is maintained. We validate these properties by means of a detailed series test plan.

When processing cold-formed sheet according to DIN EN 10130 (DC04), we mechanically achieve drawing ratios that enable a cup formation with a diameter-to-height ratio of 1:1.5. Physically, this process is controlled by the lubricant viscosity and the blank holder pressure in order to prevent the radii from thinning out. Exceeding the material-dependent yield point leads to microcracks in the base area, which makes the drawn parts unstable for assemblies under continuous load.

A constant sheet thickness is crucial as it mechanically defines the drawing gap between the drawing punch and the drawing die and thus homogenizes the frictional forces during the forming process. Physically, falling short of the thickness leads to reduced resistance to wrinkling, while exceeding it increases work hardening inadmissibly. Karl Naumann GmbH strictly monitors these parameters in order to guarantee the repeat accuracy of drawn metal parts.

Cracking is usually caused mechanically by drawing radii that are too small or insufficient lubrication, which physically blocks the material flow over the die edge. The resulting tensile stress exceeds the local strength of the material, particularly in the case of drawn parts with sharp design edges. We minimize this risk with optimized radius geometries to ensure the visual and technical quality of the drawn sheet metal parts.

The drawing radius influences the local material thinning mechanically; a radius that is too small weakens the cross-section physically due to excessive elongation. This controlled wall thickness distribution is crucial to ensure the load-bearing capacity of the caps under point loading. A technical exclusion criterion is a wall thickness reduction of more than 25%, as this massively restricts the service life for fatigue-resistant assemblies in the furniture sector.

The process capability is evaluated by statistically monitoring the flange geometry using SPC, with a Cpk value of greater than 1.33 being the target. Mechanically, this ensures that the drawn parts for automated feeding fit exactly into the assembly fixtures. Deviations in the reproducible geometry lead to jamming in the automatic assembly machine, which unacceptably reduces the productivity of component assembly.

For deep-drawn parts in the visible area, maximum roughness is required in order to mechanically guarantee a flawless surface after pickling or painting. Physically, drawing grooves must be avoided, as these act as notches and detract from the aesthetic appearance of the drawn metal parts. Karl Naumann GmbH relies on specialized drawing media to eliminate surface defects in the tool.

We use 3D optical measurement in combination with ultrasonic wall thickness gauges to verify the defined wall thickness mechanically and physically. This scope of testing by characteristics ensures that there is no unacceptable weakening even in the critical transition zones. A faulty wall thickness profile leads to rejection during the initial sample inspection.

The initial sample test report provides technical proof that the drawn parts achieve the specified dimensions and strengths in series production under real conditions. Mechanically, this validates the tool concept, while the documented traceability ensures the material quality. Without this proof, there is a high risk of incompatibilities during component assembly for the purchasing department.

The design is based on an optimization of the controlled wall thickness distribution in order to achieve high mechanical dimensional stability with low material usage. Physically, work hardening in deep drawing is used to increase the wear resistance of the functional surfaces. This guarantees reliability for durable assemblies over the entire product life cycle.

When processing micro-alloyed steels in accordance with DIN EN 10025, we achieve mechanical drawing degrees that are characterized by a cross-section reduction of up to 45% in the first draw. Physically, this requires precise coordination between the drawing die geometry and the blank holder pressure in order to control the material flow without bottom tearing. Exceeding these physical limits leads to cracking, which destroys the holding force of the drawn parts in the joining technology.

A greater sheet thickness increases the mechanical rigidity of the flange, which physically distributes the surface pressure more evenly during the screw connection. The defined wall thickness in the frame area directly determines the resistance to radial expansion. An exclusion criterion for drawn parts with a flange is uneven material distribution, as this leads to one-sided failure of the fastening technology.

Collar pulling is necessary if the material thickness of the base plate is not mechanically sufficient to accommodate enough threads for a secure screw connection. Physically, the axial extraction of the material increases the effective thread length. Incorrect design leads to cracks forming at the edge of the collar, which seriously jeopardizes the load-bearing capacity of the assemblies.

Wrinkling occurs mechanically when the tangential compressive stresses in the flange area exceed the stability limit of the sheet metal, usually due to an excessively large draw gap dimension. Physically, the material is not sufficiently slowed down by the blank holder and builds up. These defects are not permitted in precision-drawn parts, as they negate the accuracy of fit during component assembly.

A small drawing radius on the drawing die leads mechanically to a high local work hardening, which increases the hardness of the edge, but physically increases the brittleness. This stable edge zone is decisive for the notch impact work of the component under dynamic load. An incorrect choice of radius provokes premature fatigue fractures, which represents a critical risk for fatigue-resistant assemblies in railroad technology.

The controlled wall thickness distribution is ensured by a validated process chain in which cup drawing is combined with precise calibration stages. Mechanically, this produces a uniform wall, which physically guarantees a symmetrical expansion force. Deviations lead to ovality, which unpredictably reduces the anchoring force of the precision-drawn parts in the application.

The process capability (Cpk greater than 1.33) is essential to mechanically ensure that the head geometry of the drawn parts remains within the tightest tolerances. Physically, this allows friction-free feeding into the setting head for riveting and clinching. An unstable process leads to plant downtime, which has a massive impact on efficiency in the automotive and mechanical engineering industries.

We use 3D optical measurement to check the reproducible geometry and hole pattern of the drawn parts according to the drawing against the CAD specifications. The coaxiality of draw-throughs is verified mechanically in this way. Each deviation is documented in the test report to prove the conformity of the drawn parts for assemblies to the technical purchasing department.

Progressive die drawing allows the integration of drawing, punching and bending operations in one tool, which mechanically maximizes repeat accuracy by remaining on the carrier strip. Physically, this allows complex drawn parts with pull-throughs to be produced in high cycle rates for large-scale production. Compared to single-draw operations, the unit costs are reduced while the dimensional accuracy increases.

Processes such as galvanizing or passivation chemically protect the drawn metal parts from atmospheric corrosion. Mechanically, a smooth surface after vibratory finishing reduces friction during assembly. Without this protection, the drawn parts corrode prematurely, particularly on the stressed drawn edges, which jeopardizes the safety of the joining technology.

In precision mechanics, we realize drawing degrees for housing components made of DIN EN 10088 stainless steel, which are mechanically characterized by extremely small drawing radii of less than 0.2 mm. Physically, this requires ultra-precise control of the drawing die movement in order to control the tensile stresses in the micrometer range. Exceeding the deformation limit leads to immediate cracking, which renders the precision drawn parts unusable for watch assembly.

Wrinkling occurs mechanically in micro-forming due to minute inhomogeneities in the microstructure of the sheet metal, which flow unevenly under the blank holder. Physically, these wrinkles lead to localized thickening, which results in clamping or tearing in the drawing die. We ensure this through a validated process chain in order to maintain the reproducible deep-drawing position even with the smallest dimensions.

An optimized drawing radius mechanically ensures a harmonious flow of force and physically prevents the formation of stress peaks in the edge zone. As these components are exposed to permanent load changes, the prevention of microcracks is crucial for the fatigue strength of the assembly. An incorrect radius design leads to premature breakage of the links, which is a technical no-go for the watch industry.

We use high-resolution 3D optical measurement to check the reproducible geometry in the sub-micrometer range against the CAD data. Mechanically, this ensures the exact centering of bores in drawn parts with pull-throughs. The results are documented in a detailed test report to prove compliance with the watch standards for measuring and testing technology.

The initial sample test report serves as binding proof that the drawn parts according to drawing meet the extreme requirements for precision and surface quality in the small series. Mechanically, it validates the service life of the micro-tools, while for technical purchasing it proves the process reliability of the drawn parts for assemblies. Without a successful drawn part with an initial sample test report, there is no series release.

The design is based on the targeted use of work hardening during the cup-drawing process in order to achieve a high mechanical hardness of the functional surfaces. Physically, this minimizes abrasive wear, which extends the maintenance intervals of the movements. This ensures the long-term reliability of precision-drawn parts in demanding precision engineering applications.