Tribology is the science of interacting surfaces in relative motion, including friction, lubrication, and wear. Hand or wear abrasion refers to the gradual wearing away or erosion of material due to repeated friction or rubbing of the human hand or fingers against another surface. Over time, constant rubbing or friction leads to the removal of material from the surface, causing it to appear worn, smooth, or sometimes even develop holes or tears.
- How is wear or abrasion tested on various surfaces?
- Why is hand abrasion hard to measure?
- What applications benefit from surface testing for wear and abrasion?
- Why are automobile manufacturers concerned with wear of surfaces in the driver’s environment?
- How does temperature affect wear on coated surfaces?
Why is hand abrasion hard to measure?
Hand abrasion is a very complex chemical and mechanical combination. The impact of the hand (finger) on the surface leads to a local mechanical crushing, followed by a friction movement. The visco-elastic material properties of the human hand, in combination with the rough and structured surface of the skin, cause high abrasion potential. In addition, hand perspiration, creams, or sanitizers create an aggressive chemical environment. This friction movement of the hand on the surface can cause high stress on the surface of a product.
How is wear or abrasion tested on various surfaces?
Wear or abrasion testing is used to evaluate the durability and quality of various surfaces such as textiles, metals, plastics, ceramics, and coatings. Techniques and tools vary according to the type of material being tested and the intended application, and the quality and functionality of finished parts or lab samples are determined according to international standards.
Rub testing is commonly used to evaluate the resistance of printed and coated surfaces to abrasion caused by the human hand on finished surfaces, printing, and labels.
Abrasion or scratch testing involves subjecting a test material to repeated cycles of abrasion against a standard abrasive material under a specified load and speed.
READ MORE about hand abrasion tribology.
How does wear testing work?
Testing wear by the human hand or other materials in a laboratory setting typically involves simulating the repetitive actions and forces that hands or objects exert on surfaces.
As an example, TRIBOTOUCH simulates human contact by using a controlled probe that applies specific pressures, speeds, and motions to the appliance’s surface. This replication of real-world contact helps test the surface’s resistance to fingerprints and wear in a precise and repeatable manner. Oils help replicate the human touch and can also be used to test how well the fingerprints can be removed by cleaning.
READ MORE about fingerprint resistance testing.
What applications benefit from surface testing for wear and abrasion?
- Keyboards are used in many applications: telephones; music systems; control panels; touchscreens; computers; and more. These are all subject to hand abrasion of markings and lettering that are critical to a product’s functionality as well as to a user’s perception of quality.
- Bank cards have printing on embossed numbers on credit cards that rub off quickly. Wear testing may involve different chemicals such as sun cream, hand sanitizer, or sweat.
- Automotive and other transport industries all rely on printed and embossed surfaces that can wear with use – automotive, aviation, railways, shipping, and construction vehicles.
- Pharmaceutical packaging and labels require safety in packaging — the information on the label of a medical bottle or device is just as important as what is actually in the item itself, and if unreadable from wear it can be hazardous to patients.
READ MORE about applications for wear testing.
Why are automobile manufacturers concerned with wear of surfaces in the driver’s environment?
The appearance of the interior surfaces of a car is an important part of the manufacturer’s brand image of the vehicle manufacturer. Worn or damaged surfaces can give the car a shabby appearance and reduce its value.
The condition of the interior surfaces can also affect the safety of the vehicle, as control panel buttons that are worn may affect functionality, cause a delayed response by a driver, or provide a distraction while driving.
How does temperature affect wear on coated surfaces?
Temperature can have a significant impact on the wear of coated surfaces, as it can affect the properties of both the coating material and the substrate material. Here are some of the ways in which temperature can affect wear on coated surfaces:
- Thermal Expansion: Coatings and substrates can expand or contract at different rates when exposed to temperature changes. This can lead to stress and cracking at the interface between the coating and substrate, which can increase wear and reduce the durability of the coating.
- Thermal Degradation: High temperatures can cause thermal degradation of the coating material, leading to changes in its chemical and physical properties. This can result in a reduction in the coating’s adhesion, hardness, and resistance to wear.
- Thermal Cycling: Repeated cycles of heating and cooling can cause fatigue and cracking in both the coating and substrate, which can increase wear and reduce the durability of the coated surface.
- Oxidation: Elevated temperatures can also lead to the oxidation of the coating material, which can cause a reduction in its mechanical properties and increase its wear rate.
By understanding the effects of temperature on coated surfaces, engineers can design more durable and reliable products that can withstand the stresses of temperature changes and reduce wear over time.
More information: FREE TRIBOLOGY BUYERS’ GUIDE
Contact: Tim@microphotonics.com