Title: Phase 7 Redesign the Solution
Course: ATEP - MMT: Module A: > Section: PHASE 7 REDESIGN THE SOLUTION

7.1.1 Identify the Variables

In this phase, the design is critically examined by noting how other designs perform to see how it can be improved. First, identify the variables that affect the performance of your design. Again this is an iterative process that requires reviewing your product many times. Input can be from testing, the evaluation of that testing and customer surveys.

Designs are critiqued and redefined, then improved during development and during the product’s life. If necessary, additional changes are made to the product during its life. Changes can occur after customers note problems with the design through letters or surveys. Product recalls happen when problems are found due to the original design creating a safety hazard.

7.1.2 Update Information

As the design of the product is adjusted, the constraints in the design brief must also be changed for the product. As you make changes, document them in the engineering notebook to create a reference and to help during the last step of communicating the results.

(MEDIA ASSET 7.B (Breaking clevis pin: car crashing/ larger pin: car stopping — brakes))

7.1.3 Determine the Materials to Be Used

What current materials exist? What emerging or experimental materials may be helpful for the product?

For example a new method and type of plating that replaces chrome plating is nickel-tungsten plating. Not only is it a stronger material but the method used to create the coating is environmentally friendly.

A decision making matrix will again help defend your selection of the best alternative solution: Why is it the optimal choice?

Using information you have gained from research and investigation, justify why the proposed solution is the best one for addressing the design specifications.

The chosen alternative will be the basis of your preliminary design. Each of the alternatives must be examined to see if it meets the design criteria, specifications, and constraints that were defined in the first step.

7.1.4 Determine the Processes to Be Used

Production processes of the full-scale design should also be considered in this phase.  By answering the following questions through research, will help you to narrow down the estimate of cost for manufacturing.  Creating a Process Flow Chart and/or Value Stream Mapping will make your analysis easier to "see."

1. What type of process will be used to create this product?
2. What is the estimate of manufacturing costs?
3. Can you reduce the cost of the components?
4. Can you reduce the cost of assembly (change the method or lower the number of steps)?
5. Can you reduce the costs of supporting production?
6. Do the current technologies and methods exist to produce the product?
7. Can current technologies and methods be adapted to produce the product?
8. Is there a need to create a new method of producing the product?

Review your initial research and look at the methods and costs that were used to create products that are similar to yours.

Review and research newer emerging technologies that might be used to reduce cost, improve design, speed up the process or be less destructive to the environment. What is the total cost to manufacture the item to include things such as electricity, water, heat, and recycling?  Countries around the world are now starting to look at the total amount of energy used to create a product  and with it the possibility of adding a new energy tax to the sale of the product.

You should also research the types of liabilities that might be encountered during both manufacturing and customer use to include environmental and health.

With the onset of the internet and Web browsing,  companies throughout the world are now offering services to assist in creating parts and products.  Quotations for every phase are quickly obtainable.  Pricing for components are readily available through sites like:  www.emachineshop.com.

7.1.5 Quality Control

Quality Control (QC) is a way to check the factors involved in the production of a product and to limit the number of defective parts. Product inspection is part of QC where the product is examined visually. Quality control emphasizes the testing of products after they are made to determine defects and then report to management who make the decision to allow or deny product release. Quality assurance attempts to improve production to avoid, or minimize, defects before they lead to rejected parts.  Tolerances are assigned to parts for manufacturing purposes, as boundaries for acceptable part sizes.  They are reviewed during the quality assurance process and checked during the quality control process.

Engineering Tolerance:

Dimensions, properties, or conditions may vary without significantly affecting functioning of equipment or a process. Tolerances are specified to allow reasonable leeway for imperfections and inherent variability without compromising performance.

A variation beyond the tolerance (for example, a temperature that's too hot or too cold) is said to be non-compliant, rejected, or exceeding the tolerance (regardless of if this breach was of the lower or the upper bound). If the tolerance is set too restrictive, resulting in most objects run by it being rejected, it is said to be intolerant.

Dimensional Tolerance:

Related to, but different from fit in mechanical engineering, which is a designed-in clearance or interference between two parts. No machine can hold dimensions precisely to the nominal value, so there must be acceptable degrees of variation. If a part is manufactured, but has dimensions that are out of tolerance, it is not a usable part according to the design intent. Tolerances can be applied to any dimension. The commonly used terms are:

Basic size: the nominal diameter of the shaft (or bolt) and the hole. This is, in general, the same for both components.

Lower deviation: the difference between the minimum possible component size and the basic size.

Upper deviation: the difference between the maximum possible component size and the basic size.

Fundamental deviation: the minimum difference in size between a component and the basic size. This is identical to the upper deviation for shafts and the lower deviation for holes.^ If the fundamental deviation is greater than zero, the bolt will always be smaller than the basic size and the hole will always be wider. Fundamental deviation is a form of allowance, rather than tolerance.

Statistical process control (SPC) is a method of monitoring and controlling the quality of a product during the production process.  The goal of SPC is to produce the product with a minimum of waste.  Periodic checking of the product as they are created and noting the information on a chart helps to determine if there is a problem in the process.  Statistical process control is applied to any process where the output can be measured to verify that it is meeting the product constraints. A SPC control chart is shown below.