Testing of ring-type guard design showed significant entrapment issues.
Design Research Engineering
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Product evaluation is essential to assert the soundness and effectiveness of the design. Product evaluation is the process of assessing the intended product's functionality, usability, to identify and remove design or manufacturing defects.

There are different stages methods of evaluation. Depending upon the nature of the product at what stage evaluations are to be done will be decided. They may be a general evaluation at the design and manufacturing stages or a critical evaluation at the time of prototype testing. Questionnaires, creation of weightage points to evaluate different functional and operational parameters are used in the evaluation process. The questionnaires may seek feedback on aspects such as functionality, feasibility, user-friendliness, durability etc.,

Usability

• Is the product design approach correct?
• Is the product usable?
• Is the product meeting the design brief?
• How close is the design to the brief?
• Is the product meeting the customer’s expectations?

Credibility

• Is the product safe to use?
• Is the product safe from copyright issues?
• Is the product following applicable standards?

Feasibility

• Is the product technically feasible?
• Is CAPEX justifiable?
• Is the product competitive?

Durability

• Is the product durable?
• Are the parts easy to change?
• Is the product amicable to change?
• Is the product easy to change?