It is not cleanliness itself that is difficult, but its verification: a component that is clean, but not demonstrably clean, cannot be used in a manufacturing operation with a verification requirement.
Cleaning and deburring components with high technical cleanliness
1 · The challenge
Why high technical cleanliness is difficult to verify
On a component with a high technical cleanliness requirement, it is not cleanliness itself that is difficult, but its verification: a component that is clean, but not demonstrably clean, cannot be used in a manufacturing operation with a verification requirement. Whether a part reaches the required cleanliness cannot be seen by looking at it — it is decided by measurable quantities such as particle count, particle size and residual contamination amount, tested by specified methods.
On a component with a verification requirement, two results have to be verified, not one: residual burr — is the burr gone? And residual contamination — is the part clean? In deburring in particular, they are confused, yet they are two questions. A component can be free of burrs and still be contaminated, and the other way around; anyone who checks only one does not know the condition of the part.
When deburring a component with a verification requirement, the burr must not only be gone — it must be demonstrable that it is gone. And the surface must not change in the process. Both at the same time is the actual task: too much pressure removes the burr and damages the component.
On a component with a high cleanliness requirement, the verification has to be reproducible, not succeed once. What counts is not that a good part reaches the result, but that every part reaches it. Where an outlier is not acceptable, a good average result is not enough — what counts is the repeat accuracy, and that it is demonstrable.
And there is a limit that belongs before the inquiry: unrealistically low residual contamination requirements are the most common reason why a task cannot be solved as posed. We say so before the quotation, not after acceptance — a cleanliness that cannot be maintained permanently is not an achievable goal, even if it could be shown in an individual trial.
2 · Engineering considerations
What we base the system design on
- 01
Workpiece fixture
On a component with a high cleanliness requirement, the parts carrier is not an accessory but an essential part of the system concept: its design engineering helps determine where spray shadow arises and whether the nozzles reach the component — especially with residual contamination requirements it is a decisive factor. At the same time it helps decide how much liquid gets into the drying at all. - 02
Residual contamination requirement
What has to be verified on the component stands at the beginning of the system design, not at its end: the required residual contamination values act on the method, the filtration, the drying and the workpiece fixture at the same time. With high technical cleanliness, the requirement thus stands before the system — what is to be verified determines water quality, drying and process monitoring. - 03
Deburring requirement
Whether a component with a verification requirement additionally has to be deburred is decided in the same technical clarification: where a burr is involved as well, water jet deburring is usually the better solution. For the verification, that means two results instead of one — residual burr and residual contamination are two different results with two different verifications. - 04
Degree of automation
All machine types can be loaded and unloaded automatically — via robots, handling or material flow and conveying. Where process reliability is required on a component, automation is at the same time a contribution to it: an automated sequence is the reproducible one. Which degree of automation makes sense, we determine together with the other factors. - 05
Water and process media
Which water quality a component with high technical cleanliness demands depends on the residual contamination requirement, the material and the downstream process — city water, softened water or deionized water (DI water). Water is thus a design area in its own right, not an accessory; where necessary, we design the complete water treatment along with it. - 06
Drying
How dry the component has to leave the system determines the effort at the end of the process chain — recirculated air, infrared drying, air blow-off or vacuum drying, designed to suit the project. With high technical cleanliness, that is no afterthought: a clean but wet component is not finished, and residual moisture in blind holes and bores, spots from residues drying on and corrosion on bare surfaces are exactly the failures that a drying designed too tightly leaves behind. - 07
Downstream process
It is not the parts cleaning system that decides how clean a component has to be, but what happens to it afterwards: whether adhesive bonding, coating or painting follows changes the requirement fundamentally — right down to the question of which water quality is needed. We therefore look not at the system, but at your production.
3 · The system concepts
Which system concepts and methods come into question
Chamber cleaning systems
ZKIf the range of parts changes and several process steps on a component with a high cleanliness requirement are to take place in one closed chamber, the chamber cleaning system can make sense — at small to medium production volumes, for bulk parts usually as flood washing within the chamber.
Immersion cleaning systems
ZTIf, on a component with a high cleanliness requirement, workpiece or bulk parts have to be immersed completely so that the process medium reliably reaches all areas, the immersion cleaning system comes into question in particular — with small components with blind holes, immersion and flooding deliver the better results. We add ultrasonic cleaning where it makes sense.
Continuous cleaning systems
ZDIf a component with a high cleanliness requirement runs in a line with continuous flow, the continuous cleaning system can come into question: the cleanliness requirement does not rule it out, it determines the design of the stages. What is achievable is decided by the process control, not by the machine type.
Rotary indexing cleaning systems
If the process on a component with a high cleanliness requirement is broken down into fixed stations and the bottleneck lies in loading and unloading, the rotary indexing cleaning system can make sense. It presupposes a defined production process with a constant process sequence.
Drying
If a component with high technical cleanliness has to go on dry, drying is part of it as a design factor of its own and not as an ingredient added at the end: recirculated air, infrared drying or air blow-off, depending on the system design — with very high drying requirements, vacuum drying comes into question. Drying is the third fixed step in the basic process, extended depending on the project by a second rinsing, a second drying or an air blow-off.
High-Precision Water Jet Deburring
Where a burr is involved on a component with a verification requirement, water jet deburring comes into question in particular: the high-pressure water jet reaches bores and internal channels that mechanical tools cannot get to — reproducibly and in cycle, which tips the balance where process reliability is required. We design the pressure according to the task, not from a catalog.
Technical cleanliness and residual contamination
Where high technical cleanliness is required on the component, the verification is part of the task and not an add-on: depending on the requirement, visual inspection, camera-based inspection, residual burr inspection, residual contamination analysis and process monitoring come into question. The first four test the part, the fifth the running process — it keeps it within the window and is thus the prerequisite for not every part having to be tested.
The principle
Why several solutions are possible for components with high technical cleanliness
None of these assignments is a rule. The machine type follows the component and the cycle — depending on production volume, cycle time, residual contamination requirement and material flow, the same component can be better placed in a different system, and there is no rule “component X, machine Y”. What a high technical cleanliness determines is therefore not the machine type, but what the verification demands: water quality, drying and process monitoring. What you see here is the consideration, not its result.
4 · What else to consider
What else has to be clarified for components with high technical cleanliness beyond the process
- 01
The verification is not carried out by whoever built the system
On a component with a verification requirement, both verifications run through one contact person, but not both through the same hands: the residual contamination analysis is carried out by an independent, accredited test laboratory, not by us. That is deliberate — our release hangs on this figure, and it should not come from us. - 02
The standard says how measurement is done — not which value your component has to reach
Where technical cleanliness is required on a component, measurement is done to VDA 19 / ISO 16232. These standards define how measurement is done, so that a value is comparable and repeatable — not which value your component has to reach. That is why we design to the specific cleanliness requirement of your component, not to the standard as such: your specification, the component and the downstream process determine the system design, the standard determines the verification. - 03
Only when the values are right does the system leave the factory
Testing is done twice: at the internal factory acceptance test (FAT) with original components and again at the site acceptance test (SAT) after installation at your site. If the agreed residual contamination values are not reached, the system is not released. Only the second acceptance test proves under your real conditions what the first one promised. - 04
Traceability down to the individual component
Where “the batch was clean” is not enough, but “this part was”, traceability down to the individual component is possible depending on the project: via barcode or DataMatrix recognition, the processing program can be selected per part and the result written back per part. That is project-dependent, not standard.
Questions and answers
Frequently asked questions about technical cleanliness
Why is the verification more difficult than the cleanliness itself?
Are residual burr and residual contamination the same thing?
Does the standard define which value my component has to reach?
Do you carry out the residual contamination analysis yourselves?
When does a cleanliness requirement count as not achievable?
Direct contact
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93186 Pettendorf
Pettendorf bei Regensburg
Fax +49 (0) 9409-777 3607
Technically responsible for this page: Kersten John — Senior Consultant Technical Cleanliness