Diagram one (1)
In diagram one the improved design is A.
The diagram represents a design for a container probably a bucket designed to hold a fluid. In the designers mind, the main idea being able to stack for compaction and occupy as minimal space as possible. It will be noted that in designing that designing for disassembly will minimize transportation costs especially in a situation where a product has to be moved for long distances to access the market (Shetty 64). The main advantage on stacking being transportation cost as is evident in both design A and B. However design A is improved comparing to design B. Here is my rationale;
Design B has a locking angle with most of the interlocking surface being in touch. Design A is optimized by adding ribs at the bottom that prevent too much of the surfaces being in touch. As a designer, a product is of concern not only when being manufactured but during handling in shipping and use (Eppinger 89).
Design A has the biggest advantage that by having added ribs, they eradicate the problem of nesting. Too much surface being in contact has the disadvantages namely; locking, increase in handling time and interference with surface finish.
The virtue of locking does not only hinder the speed at which the components can be separated individually in the event that they are stacked but can lead to complete locking if inflexible material is used or close tolerances are involved (Shetty 123). As a result of locking it can be appreciated that to the person who unsticks these commodities will have to take longer time to unstick design B as opposed to design A. Lastly design B is most likely to suffer interference in the surface finish on the inside and outside, a poor surface finish will lead to lower market value if the finish is used as a marketing advantage of a given product (Ashby 86).
Diagram 2
This diagram indicates a component most likely to be fabricated as a sheet metal, most likely a washer type piecework that is fastened on both ends either by screws or nut and bolt. Design B is a more improved version than design A. Here is my rationale;
Despite both designs destined for a common application, design B is designed for symmetry or ease for orientation unlike design A which is asymmetrical or rather reoriented. Using a line of symmetry that cuts across the three holes it can be noted that in design A that the piece is protruded on one side, on design B symmetry is observed with the protrusions occurring on opposite sides of the symmetry.
Design for symmetry has the advantages that the piece to be produced is easy to handle on the machine as the machining forces will always be balanced, moreover it has the advantage that during assembly and disassembling less time is taken since the direction of fitting is of less concern (Lefteri 64) (Eppinger 213). Fitting such a piece on the final location is dependent on the two holes at the periphery, by placing design B from any direction it works well unlike design A where the piece can be fitted in that direction only.
Design B I symmetrical allowing the manufacturer to center the piece at the middle with the machining lathe, this does not result in unbalanced forces that may wobble the piece due to lack of symmetry. Design A would require excessively high grip to work effectively in the machining lathe thus increasing time to handle and it may lead to more errors compromising on the set tolerances. An increase in errors may lead to rejects and further increase production costs (Shetty 24) (Eppinger 213).
Design three (3)
This design is that of a component likely to be applied as a handle of a bigger product. The design modifications being that of the methods used to fit between the handle and the component. Taking the upper component as a handle, it can be said that the handle in design A is fitted in two round holes while design B is fitted in two holes one being round and the other being slotted. Design B is better than design A, here is my rationale;
Design B is better as it reduces the tolerance requirements required of the handle. It can be noted that by introducing such a modification that the distance between centers in design A is fixed as opposed to that of design B which are variable to a certain degree. Design B allows the manufacturer to machine or produce the handle with less tolerance as that used in design A. Design A, operating under the fixed distance between centers is required to machine the handle with the highest accuracy as possible to ensure that the two components mate (Ashby 12).
Factoring in precision in distances of a component manufactured, it can be noted that higher precision parts will increase the production costs of a component (Lefteri 213), who wants that anyway? Therefore it’s likely that if handles will suffer length changes if they are likely to be manufactured from a flexible material, however since part B is a load bearing component it is likely to be hard and machined to close tolerances and being unlikely to suffer dimensional changes. The handle is more likely to suffer dimension changes since the arms increase the effort distance. During assembly, it will be appreciated when fixing the components as a less accurate handle in design will fit with little precision unlike in Design A where the parts may need re-machining or be rendered useless. Re-machining and defective parts will lead to higher production costs and hence lead to more price at the selling (Eppinger 166).
Diagram 4
This diagram indicates a part that is likely to be used in securing an angle. It is likely to be used to secure a longitudinal member to a transverse base. Design A employs two separate holes while design B employs a single hole and rather slotted. The base part is common among the designs indicating it as a more rigid point of joining members. Design A is a better design than B. here is my rationale;
The two designs look to be used in members that require fixing and strength being a design attribute, the components needs to be designed for strength. Design B uses two small holes while design B uses a slotted hole. Design A is better as opposed to design B since the use of two single holes gives more strength to the part. Design B weakens the component by use of a slot thus making that part prone to failure during loading.
Taking the two designs in their most likely point of operation, it can be noted that screws or nuts and bolts are the likely fasteners to be used in any scenario. Design A has the advantage that by using two small holes in the piece are likely to attach to a member with less probabilities of failure as the overall mass of material removed from the part is minimal. Design B will however not offer the much strength required since the creation of a slot lead to higher material removal rendering the component less sturdy (Shetty 34).
In the event of loading, Design A and B can fail if fasteners fail at that point, however Design B can fall from other things such as the failure of the part itself through bending. Design B would offer flexibility in component being fastened within a range of dimensions; however such a case affects the strength at a joint and may render Design B a weak component.
References
Ashby, M. F. Material Selection In Mechanical Design. Oxford UK: pergamon press, 1992.
Eppinger, K. T. Ulrich and D. Product Design And Development, 5th Edition . New York: Mc GrawHill, 2011.
Lefteri, Chris. Making it : manufacturing techniques for product design. London: Laurence King Pub, 2012.
Shetty, Devdas. product design for engineers. Boston MA: Cengage Learning, 2016.
No comments:
Post a Comment