Requirements for stamped and deep-drawn parts
After stamping and deep-drawing, drawing greases, oils and particles adhere to the parts. They have to be removed reliably before further processing — usually in step with the cycle, in series ranging from small batch sizes up to multi-year long-runners that run 365 days a year over several years. Cleaning here is therefore not a one-off step but a reproducible process that has to fit the production.
The choice of stamping and drawing oil already affects later cleaning: together with ZET-Chemie, we find the oil that secures the forming process and is then easy to remove. ZET-Chemie offers forming oils developed specifically for rolling and drawing processes; ZET clean 56S can even be used cold as a fine-blanking medium. For inline cleaning directly from the stamping strip, two technologies are equally suitable: the high-pressure cleaning systems from RL Automation and Ossberger’s Single-Piece-Flow — the parts are cleaned immediately after stamping. The Ossberger technology is used, among others, at Dorma Kaba AG.
In addition, RL Automation has developed strip-oiling systems specifically for stamping processes: minimal lubrication ensures long tool service life and optimal multi-stage stamping processes. This way, process-appropriate oiling and cleaning come from a single source.
Typical parts and contamination
From this industry, we primarily clean:
- Parts: contacts, sheet-metal formed parts and springs
- Materials: steel, stainless steel, brass, aluminium, tin-plated and galvanised steel as well as copper
- Contamination: drawing greases and oils, stamping slivers (fine metal chips forming at the cut edges) and metal abrasion
It is precisely the combination of filmic residues (oils, greases) and particulate residues (slivers, abrasion) that makes the task demanding — both have to be removed reliably without altering the part.
Suitable processes
Which process fits best depends on the part, the contamination and the batch size — we advise on a technology-neutral basis. For this industry, the following are particularly relevant:
- Wet-chemical cleaning — aqueous or solvent-based cleaning, targeted at drawing greases and oils
- Vibration cleaning — cleaning and deburring by vibration
- High-pressure cleaning & deburring — cleaning and deburring with the high-pressure water jet (RL Automation systems)
Downstream processes: what cleaning contributes to
For stamped and deep-drawn parts, cleanliness determines the following process step. We clean for practically all downstream processes:
- Coatings of all kinds — PVD, CVD and electroplating processes
- Welding, bonding as well as assembly and packaging
- further machining and forming processing steps
Because each of these downstream operations places different demands on filmic and particulate cleanliness, we always define the cleanliness target from the downstream process — not the other way around.
Measurement and quality assurance
For stamped and deep-drawn parts, cleanliness is a verifiable, documentable process step. TeSe carries out some of the tests in-house — contact angle measurement to determine the surface tension (filmic cleanliness) as well as inspections under a high-resolution microscope with various light sources. More advanced tests such as residual-contamination determination according to VDA 19 (particulate and filmic cleanliness) or — for the highest requirements, e.g. in sensor manufacturing — scanning electron microscopy (SEM) are mostly customer-defined processes that TeSe partly supports.
This way, the cleaning result can be demonstrated in a traceable manner and kept reproducible across the series.
Practical example
In the manufacture of electrical contacts, we clean directly in the line after tin-plating: excess tin and stamping slivers are removed so that the contacts can then be loaded into plastic carriers on assembly machines without disruption. Here, cleaning is therefore not a cosmetic but a functional step — it ensures trouble-free automated assembly.
Frequently asked questions
What contamination arises during stamping and deep-drawing? Above all drawing greases and oils as well as stamping slivers (fine metal chips at the cut edges) and metal abrasion — i.e. a mixture of filmic and particulate residues.
How is cleanliness checked? Via contact angle measurement (filmic), residual-contamination determination according to VDA 19 (particulate and filmic) and, if required, inspections in the scanning electron microscope.
Can parts be cleaned directly from the stamping strip? Yes. With Ossberger’s Single-Piece-Flow, each part is cleaned individually and immediately after stamping.
Does the forming oil affect the cleaning? Yes, considerably. That is why we coordinate the forming and drawing oil with ZET-Chemie so that it secures the process and is then easy to remove.
Test the process at TeSe
Whether a process meets your industry’s requirements on your actual part is shown by a trial: 1–2 hours of testing free of charge. In-depth feasibility studies: CHF 1’200 per day, 50% creditable against a machine purchase.
Documents & videos
Datasheets & brochures
Vibration & inline cleaning — Ossberger
Cleaning baskets
Videos
Process chemistry
Vibration cleaning