Parts cleaning

Key takeaways

Parts cleaning belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Parts cleaning to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Parts cleaning from memory before moving on to harder problems.

Reference excerpt

Parts cleaning is essential in many industrial processes, as a prelude to surface finishing or to protect sensitive components. Electroplating is particularly sensitive to part cleanliness, since molecular layers of oil can prevent the coating adhesion. Cleaning processes include solvent cleaning, hot alkaline detergent cleaning, electro-cleaning, and acid etch. The most common industrial tests for cleanliness of machinery is the water-break test, in which the surface is thoroughly rinsed and vertically held. A quantitative measurement for this parameter is the contact angle. Hydrophobic contaminants such as oils cause the water to bead and break up, allowing the water to drain rapidly. Perfectly clean metal surfaces are hydrophilic and will keep an unbroken sheet of water that does not bead up or drain off.

Definitions and classifications For the activities described here, the following terms are often found: metal cleaning, metal surface cleaning, component cleaning, degreasing, parts washing, and parts cleaning. These are well established in technical language usage, but they have their shortcomings. Metal cleaning can easily be mixed up with the refinement of un-purified metals. Metal surface cleaning and metal cleaning do not consider the increasing usage of plastics and composite materials in this sector. The term component cleaning leaves out the cleaning of steel sections and sheets, and finally, degreasing only describes a part of the topic, as in most cases, chips, fines, particles, salts, etc. also have to be removed. The terms "commercial and industrial parts cleaning", "parts cleaning in craft and industry", or "commercial parts cleaning" probably best describe this field of activity. There are some specialists who prefer the term "industrial parts cleaning", because they want to exclude maintenance of buildings, rooms, areas, windows, floors, tanks, machinery, hygiene, hands washing, showers, and other non-commercial objects.

Elements and their interactions

Cleaning activities in this sector can only be characterized sufficiently by a description of several factors. These are outlined in the first image above.

Parts and materials to be cleaned First, consider the parts to be cleaned. They may comprise non-processed or hardly processed sections, sheets and wires, but also machined parts or assembled components needing cleaning. Therefore, they may be composed of different metals or different combinations of metals. Plastics and composite materials can frequently be found and indeed are on the increase because, e.g. the automobile industry, as well as others, are using more and lighter materials. Mass can be very important for the selection of cleaning methods. For example, big shafts for ships are usually cleaned manually, whereas tiny shafts for electrical appliances are often cleaned in bulk in highly automated plants. Similarly important is the geometry of the parts. Long, thin, branching, threaded holes, which could contain jammed chips, feature among the greatest challenges in this technical field. High pressure and the power wash process are one way to remove these chips, as well as robots, which are programmed to exactly flush the drilled holes under high pressure.

Contaminations The parts are usually covered by unwanted substances, contaminants, or soiling. The definition used is quite different. In certain cases, these coverings may be desired: e.g. one may not wish to remove a paint layer but only the material on top. In another cases, where crack proofing is necessary, one has to remove the paint layer, as it is regarded as an unwanted substance. The classification of soiling follows the layer structure, starting from the base material:

Deformed boundary layer, > 1 μm Reaction layer, 1–10 nm Sorption layer, 1–10 nm Contamination layer, > 1 μm See illustration 2: Structure of a metallic surface The closer a layer is to the substrate surface, the more energy is needed to remove it. Correspondingly, the cleaning itself can be structured according to the type of energy input:

Mechanical – abrasive: blasting, grinding Mechanical – non-abrasive: stirring, mixing, ultrasound, spraying Thermal – reactive: heat treatment much above 100 °C in reactive gases Thermal – non-reactive: temperature below 100 °C, increased bath temperature, vapor degreasing Chemical – abrasive/reactive: pickling in liquids, plasma-assisted, sputter-cleaning, electropolishing Chemical – non-reactive: organic solvents, aqueous solutions, supercritical CO2 The contamination layer may then be further classified according to:

Origin Composition: e.g. cooling lubricants may be composed differently. Single components may account for big problems, especially for job shop cleaners, who have no control over prior processes and thus don't know the contaminants. For example, silicates may obstruct nitriding. State of aggregation Chemical and physical properties The American Society for Testing and Materials (ASTM) presents six groups of contaminations in their manual "Choosing a cleaning process" and relates them to the most common cleaning methods, the suitability of cleaning methods for the removal of a given contaminate is discussed. In addition, they list exemplary cleaning processes for different typical applications. Since one has to consider very many different aspects when choosing a process, this can only serve as a first orientation. The groups of contaminants are stated:

Pigmented drawing compounds Unpigmented oil and grease Chips and cutting fluids Polishing and buffing compounds Rust and scale Others

Charging In order to select suitable equipment and media, it should be known also which amount and which throughput have to be handled. In larger factories, little amounts are virtually ever cleaned economically . Additionally, the pricing method needs to be determined. Sensitive parts sometimes need to be fixed in boxes. When dealing with large amounts, bulk charging can be used, but it's difficult to achieve a sufficient level of cleanliness with flat pieces clinging together. Drying can also be difficult in these cases.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Parts cleaning

Start with the simplest possible case. Write down what Parts cleaning claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Parts cleaning before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Parts cleaning ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Parts cleaning

In research: Parts cleaning appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Parts cleaning in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Parts cleaning is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cleaning, Industrial processes, Metalworking, so understanding it makes those chapters shorter.
In everyday life: Look for Parts cleaning outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Parts cleaning in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Parts cleaning means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Parts cleaning out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Parts cleaning in simple terms?

Parts cleaning is essential in many industrial processes, as a prelude to surface finishing or to protect sensitive components. Electroplating is particularly sensitive to part cleanliness, since molecular layers of oil can prevent the coating adhesion.

Why does Parts cleaning matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Parts cleaning?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Parts cleaning.