Tips to Help You Design for Wear Resistance and High Wear Applications

How to design parts for machines or components of larger systems?

This is a very good question that is taught in universities, technical schools, vocational schools, special courses, and other available teaching methods. This knowledge can also be found on the internet: on discussion forums, groups, or in the form of tutorials on YouTube. This is somewhat dry knowledge, which allows to systematically describe what shapes a particular part should have and how it should fit into a larger (or smaller) system.

Its development and improvement is a continuous process, which is a challenge faced by every professional in the CNC and production industry. But in addition to the project, there is also the area of materials science, which directly affects durability – very often on a macro scale. Different materials have different parameters, and finding the ideal compromise in the process of designing parts for machines is a big challenge. Only the combination of knowledge from both areas allows for the design of durable – to put it bluntly: well-thought-out – parts.

Although they are not as (in)famous as the "dancing Tacoma bridge" or incompatible CO2 exchangers on board Apollo 13, it is their durability that makes them unnoticed and they simply perform their tasks.

Part Design: From Sketch to Final CAD Project

Part design begins by understanding the task of a particular element in a larger system – it is very rare that an object is monolithic and does not operate in relation to others. Dimensions, shapes, radii, surface structure – these are just a few parameters that should be specified in a good technical drawing or technical documentation of the project. One of the good practices at every stage of design is to place the object in the context of the system in which it operates – with the indication of directions, acting forces and ranges of movements in its environment.

This helps to avoid situations where some part does not fit or causes problems during operation – e.g., it collides with other objects. This, of course, requires knowledge of the system itself, which is why parts are rarely designed without context. Hence, seemingly unnecessary cuts or shapes become clear only after placing the components in their places. A good example is the timing case in a car engine – made of metal alloys or polymers – it may look like a structure crossed by pins and bolts with numerous cutouts.

Only after placing it on the engine block does the purpose of each of these elements become clear, and more importantly – necessary. With this in mind – it is possible to design a 3D model of a part in CAD (computer-assisted design) software, from which it can be converted into G-Code understandable for cutting devices (especially CNC). Many processes require an additional step, which is part prototyping.

Creating objects with dimensions specified in the project using cutting devices is sometimes labor- and time-consuming, but it allows for the evaluation of the correctness of the project, and sometimes also – of selected materials. Currently, 3D printing is more often used for "quick" prototyping – due to its high availability and noticeably lower entry threshold, it is a technology that allows for quick (relatively) production of physical objects based on CAD files and their compatibility assessment in a larger system. This is an additional stage that helps to avoid errors in production, and thus – to reduce the costs of possible mistakes that can be prevented in this way.

Additionally – such prototyping allows to assess the impact of forces on individual elements and estimate the lifespan of specific parts; it can also affect the decision that some elements – in order to ensure the correct operation of the entire system – should be made of materials with higher strength.

Choosing the Right Materials and Production Technology

The next element that contributes to the production of wear-resistant parts, particularly those exposed to large forces, is the selection of appropriate materials. Modern materials science struggles with the problem of finding alloys, polymers, or composites that will be the best combination of:

• low weight,
• high strength,
• ideally the best mechanical properties,
• at the lowest possible (or at least: adapted to the rest of the system) price.

Apart from extreme cases (e.g., heavy construction equipment, space industry, or production for military aviation), this is a form of compromise. Parts with very good mechanical parameters are usually heavy and although their production cost is not very high, not every application requires such high strength. For decades (if not centuries), the commonly used material that meets the above requirements – apart from low weight – were iron alloys (including steel).

However, the requirements changed over time and with the development of industry, especially the automotive and aviation sectors, the demand for lighter materials, which would be a compromise between the four features mentioned above, increased. The first polymers (e.g., bakelite) or the widespread use of relatively light aluminum (and over time specialized alloys, high-performance polymers, or composites) increased the availability of materials with different properties. Thus – selecting the right one for the project became (somewhat) easier.

Thanks to the achievements of materials science, it is easier to find a relatively light material, with good mechanical properties and at an acceptable price (aluminum), just as finding one that is light, cheap, and has sufficient strength (e.g., high-performance polymers) is also not a problem. However, choosing the right material for the production of designed parts requires knowledge and experience.

Again – both knowledge of the entire system is required (e.g., whether all parts should be made of metals of similar nobility, which makes it easier to avoid corrosion) and the environment in which they will be used (dry, humid, salty, etc.).

This affects the choice of the right material:

• for example, if a part is to work in a dry environment and is characterized by high mechanical strength, and weight is not a problem, a good choice may be steel, especially stainless,
• if the part should be as light as possible and it will be subjected to low forces, a reasonable choice of material will be one of the easy-to-cut polymers,
• if the part is to be light, durable, and have outstanding mechanical properties, then the obvious choice for many engineers and designers are titanium alloys, which are very expensive, but in some industries, the parameters are more important than the price (e.g., military aviation).

And so, the choice of material has a direct impact on the wear rate of a particular part, largely due to the different resistance to abrasion or stress, which characterizes different materials. Although finding a balance between these properties can sometimes be a far-reaching compromise, it is a challenge that materials scientists, especially those specialized in cutting, will easily cope with – such as those working in RADMOT.

Additional Surface Enhancement Processes

The selection of appropriate materials for the production of parts with high wear resistance is often one of the important stages. However, knowledge of the environment and system in which a particular part will work can influence the decision to carry out additional surface enhancement processes. Apart from a few exceptions, the group of corrosion-resistant metals is not too large, so the decision is often made to further improve their surface to protect against oxidation processes.

Additionally, contact with chemically active substances or exposure of certain surfaces to high friction may require additional polishing or galvanic treatment of elements. There is a wide range of processes that allow for the improvement of the surface protection of parts and the increase of its technical parameters, and thus – ensuring longer service life.

Among the most commonly used, it is worth mentioning surface enhancement processes:

• steel – saturation with elements (galvanizing, chroming, etc.) improves corrosion resistance and sometimes improves the aesthetic qualities of parts,
• aluminum and titanium – anodizing allows for increasing the already acceptable corrosion resistance, and additionally reduces friction and improves mechanical resistance.

The selection of appropriate surface enhancement processes is important from the perspective of part durability during operation. This, in turn, translates into lower costs and stable performance.

One order, many benefits - this is how you work with RADMOT

At RADMOT, we offer CNC milling services, CNC turning services, as well as many additional services, including washing, aluminum anodizing, laser marking and assembly. We have at your disposal over 80 modern machines in our machine park, all from renowned manufacturers. Download the presentation and check on which machine tools we produce CNC turned parts and CNC milled parts.

Contact us and tell us what you need. We have been providing CNC services for almost 40 years. Our valuation is completely free. And if you're in doubt about which technology will work best for you, our expertise is at your service.