Material selection
Material selection
The choice of materials plays a central role, even a small mistake can lead to increased costs or failure of the component and the equipment.
The material selection should bring following benefits:
- know-how acquisition
- more reliability
- more safety
- longer working life
- cut incidental damages
- lower cost of the component
- less maintenance
- weight loss
and should also avoid:
- greater workload
- dealing with new materials
- redesign due to new materials (tools, injection moulding tools, production planning, etc.).
To best schematise the concepts to be considered in a proper material selection, we have decided to make use of a chart. This is diveded into 7 different levels / procedures (from 0 to 6), that can be used for the material selection. The chart specifies also what are the advantages of the methods and the disadvantages of the others.
Although this method have allowed us to travel a long & successful way to the present days, it does not have the presumption to solve all the problems or to indicate the most correct way to go. This method only wants to indicate the steps, which according to our point of view, are to be followed in the material selection and / or in the design of a component.
Description of the material selection levels
Level 0
Classic example, unfortunately still very popular, I try and then I see what happen. If we analyse the time used and the final price of the parts, it can be noted that it is not worth proceeding following this method.
Level 1
If we analyse the topicality of knowledge and the improvements obtained, we see respectively that the first criterion is very old and the second one does not lead to any improvement.
Level 2
If we analyse this level, we can see that it is really possible to obtain a high quality solution but in most cases the reference example cannot be used and the final price of the parts, added to the time needed and the costs incurred are very high.
Level 3
The risk of failure is high and there is a risk of not considering the values of the materials that are truly important for the specific application.
Level 4
From this level onwards we begin to have the first advantages. The risk of failure starts to drop and at the same time there is a saving on the final price of the parts.
Level 5
The risk of failure and the final price of the parts is further lowered and at the same time a high price optimisation and efficiency are obtained.
Level 6
It is the highest level of this material selection. Both efficiency optimisation of the parts is obtained and reducing the final price of the parts. The customer’s time investment is reduced to a minimum since corporate Wolf Kunststoff-Gleitlager GmbH will perform all the estimates required for the correct selection.
Chart of the material selection levels
| ' | - | 0 | 1 | 2 | 3 | 4 | 5 | 6 |
| Denomination | try & error | old monkey | copy & improve | Comparison | Optimisation | Total | Complete | |
| Example | - | Automatism: chain guide = PE1000 | Transfer of application examples (e.g. from nature -> bionics) | Comparison of the values of the materials with each other | Comparison of the values of the materials with those of the current material | Comparison of the values of the materials with those of the component e.g. loads/deformations | Comparison of the values of the materials with those of the component e.g. loads/deformations | |
| Type of decision | attempt | Recourse | Transfer and improvement | Comparison: better / worse | Comparison better / worse | Calculation & design | Calculation & design | |
| Basis for decisionmaking | None | Experience | Similar application | Supplier data | Supplier data, previous experience | Material characteristics, load & deformation data | Material characteristics, load & deformation data | |
| Level of decision | - | Application own area | Foreign area application | Material characteristics | Material characteristics | Component or material loads/deformations | Component or material loads/deformations | |
| Depth of decision level | 0% | 10% | 70% | 60% | 70% | 80% | 80% | |
| Knowledge source | Attempt | Internal knowledge | Combine external with internal knowledge | External knowledge | External, internal knowledge | External, internal knowledge | External, internal knowledge | |
| Knowledge quality | 90% | 70% | 80% | 90% | 95% | 100% | 100% | |
| Current knowledge | 0.5 years | 10 years | 3 years | 2 years | 2 years | 2 years | 2 years | |
| Knowledge availability | 0% | 100% | 30% | 70% | 75% | 50% | 50% | |
| Knowledge price | Trials cost | None | None | None | None | Training required | None, because external | |
| Risks' causes | Time and cost intensive | No improvement | Example not transferable | Unsuitable / not decisive material properties used | Material characteristics inaccurate | Material properties inaccurate, parameters information inaccurate | Parameters information inaccurate | |
| Risk of failure | 80% | 20% | 30% | 30% | 20% | 10% | 5% | |
| Chance | None | None | Novel solutions | Higher load possible | Higher load possible | High optimization price / performance | Optimal solution price / performance | |
| Investment client - money | 5% | 10% | 50% | 30% | 40% | 50% | 65% | |
| Investment client - time | 90% | 5% | 45% | 50% | 40% | 20% | 15% | |
| Solution quality | 70% | 70% | 120% | 70% | 80% | 90% | 100% | |
| Parts’ price | 150% | 100% | 110% | 90% | 90% | 80% | 70% | |
| Innovation | Possibly regression | None | High | Medium | High | High | High | |
| Support WKG | Samples | Not required | Application catalogue | Relative material comparison | Specific material comparison | Training, documents, calculation forms | Questionnaire |
What’s now?
Now that we have described how the different levels differ from each other, let’s elect the macro parameters that are important for the component and we give them a value.
The points found in the following table are first attributed on basis of the selected parameters and then added together, thus indicating the minimum level of choice required for the material selection.
Obviously, the indicated values are to be understood as an example. These values are subject to variations in relation to companies, industrial fields, etc.. Each company should adapt the values to its own needs.
Example of a decision support chart, for components made of plastic materials
| Decision support | |||||||
| Properties | Parameters | Selection | Importance points | Minimum level material selection | |||
| Option A | Points A | Option B | Points B | ||||
| Duty cycle | low, sporadic | 0 | high, constant | 1 | B | 1 | Level 4 |
| Operating temperature [°C] | <60 | 0 | > 120 | 2 | A | 0 | |
| Load level [MPa] | <5 | 0 | > 50 | 1 | A | 0 | |
| Specific material costs [€/kg] | <50 | 0 | > 130 | 1 | B | 1 | |
| Safety - Failures | Sporadic / none | 0 | Constantly | 2 | B | 2 | |
| Shape parameters | Simple / bushing | 0 | Medium / roller bearing | 1 | A | 0 | |
| Interchangeability of the component | Simply, fast | 0 | Not possible | 2 | A | 0 | |
| Function for the entire system | Subordinate | 0 | Key function | 2 | A | 0 | |
| Sum =4 | Specific material comparison |
If the sum is > 6 then the suggested minimum level of the material selection is 6.
Material selection options
Samples
Application catalogue
Here you will find some application examples of the ZEDEX® materials sorted by application.
Download the application catalogue
Relative material comparison
Specific material comparison
Our Experts - Consulting of Wolf Kunststoff-Gleitlager
Training, documents, calculation forms &/or tools
Questionnaire
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