Section One
Design for manufacturing a concept that seeks to minimize the cost involved in manufacturing an item. As a concept in engineering, design for manufacturing also seeks to reduce the difficulty when manufacturing a product. The design for manufacturing concept is concerned with the reduction of the overall cost of production that results from parts that are used in the manufacturing process. In order to achieve this, the design for manufacturing concept seeks to minimize the complexities in the processes that might impede manufacturing operations by using common primary axes and datum features (Porter 2).
On the other hand, the design for assembly concept in engineering entails altering the design process so that there is ease in assembly of the final manufactured parts into the desired product. The design teams, using this concept seek to produce designs of products that transition easily into production while incurring a minimum cost. This is achieved by focusing on the handling, number of parts and the ease with which these parts will be assembled into the finished product (Stienstra 4). Unlike the design for manufacturing concept that is concerned with the reduction of overall production costs that emanates from the parts used, the design for assembly concept is concerned with the reduction of the product assembly costs.
Together, the two concepts are referred to in an umbrella term, design for manufacturing and assembly. This concept is very important to the manufacturing and assembly in the engineering industry. The use of the design for manufacturing and assembly concept has a great impact on the outcome of the production process. Firstly, there are less parts of the final product to be designed, documented and revised. This saves on the usage of materials, as will be highlighted later and also reduces the processes that are required in the production process. Additionally, the use of this concept reduces the bill of material cost because the design of less parts of the final product results in the usage or less materials. This also reduces the cost of handling, inspection and storage because of the reduced parts to be received.
The use of the design for manufacture and assembly concept also has an impact on the labor requirements of the production process. There is decreased need of labor because of the overall effect of the concept on the production process. This also has an implication on the energy requirements of the manufacture of parts and the subsequent assembly of these parts into the final product. The design for manufacture and assembly concept is also important to the production process because creates decreased complexity in the production process. As such, the assembly instructions that are packaged together with the parts in cases where parts are exported to be assembled elsewhere are simple and easier for the consumers to comprehend. The other impact of this concept is that it results in higher quality of the finished product. With decreased complexity and simple instructions for assembly reduces the propensity for errors in the assembly process.
These entire impacts combine together to affect the economic perspectives of the production process. As a result of the design for manufacturing and assembly concept, companies can enjoy higher profit margins. This makes such organizations more competitive and better performers in the in the market.
Besides the impact of the concept, it also has several advantages that make it important to the in engineering. The design for manufacturing and assembly concept offers quantitative methods through which the design process can be assessed. Through the assessment of the design process, improvement can be made so that the cost effectiveness of the manufacturing and assembly process. Additionally, the concept offers communication tools through which information can be transmitted to other departments and engineering disciplines. The use of design for manufacturing and assembly leaves a greater role to be played by other groups such as manufacturing while the product is still in the design phase. Lastly, the other advantage of the design for manufacturing and assembly concept is that it allows designers to identify the hidden costs before they commit to any design. This is especially so given that almost three quarters of the cost of production for any product is established in the engineering phase of the product.
Statistical process control is another concept that is ultimately important to manufacturing processes. As used in manufacturing, statistical process control entails the use of statistical methods in quality control on a manufacturing line (Thompson 229). This is done in order to monitor and apply corrective measures as required in a manufacturing process. By doing this, one ensures that the production line operates effectively and achieves the full potential (Webber & Michael 156). The importance of statistical process control in manufacturing process is its ability to use minimum waste resulting from scraps and reworks in producing an end product that conforms to the standards (Pena-Rodriguez 2). This implies that the use of statistical process controls benefits a manufacturing plant by ensuring that the end products conform to the standards established. Additionally, the use of statistical process control allows the manufacturing plants to minimize on wastes that result from excess scrap and reworks of nonconforming products. Several techniques are used in statistical process control. These techniques allow the manufacturing process to achieve different control thresholds by determining the extent of certain variables.
As used in manufacturing, Cp describes the process capability in a manufacturing plant. This indicator describes the capabilities of the process. On the other hand Cpk is the process capability index (Booker, Raines & Swift 57). This is a function of Cp. It is a modification of Cp in order to indicate the effect that a non-centered distribution has on the process. These two indicators can be used in the monitoring of process in order to determine the effectiveness of such process, and also inform the corrective actions that are required (Viswanadham 101). Cpk can be used to determine the extent to which a process is operating close to the limits specified in relation to the process’s natural variability. A large process capability index implies that there is a low probability that any of the items in the process will feature outside the specified limits. This indicator also shows the consistency of a particular process. This implies that this index can be used to determine any variability in the process, thereby informing the necessary corrective actions (Joglekar 148).
Section Two
This symbol of geometric tolerance shows straightness. This symbol is used to describe conditions where the elements of any given surface are a straight line.
This symbol of geometric tolerance shows flatness. This symbol is used to describe surface conditions where all the elements are in one plane.
This symbol of geometric tolerance shows circularity. This symbol is used to describe conditions of a surface where every point of the surface is intersected by a plane.
This symbol of geometric tolerance shows cylindricity. It is used to describe the conditions of surfaces of revolutions where all the parts of the surfaces are located equidistant from the common axis.
This symbol of geometric tolerance shows parallelism. This symbol is used to describe surface conditions where all elements are equidistant at every point from an axis or a datum plane.
Section Three
The ISO classification of limits and fits entails a coordinated system of shaft and hole tolerances that are used in manufacturing and engineering in gages, cutting tools and material stock. Under this classification, hole based fits feature four preferred hole tolerances namely H11, H9, H8 and H7 (Richards 147). Although the shaft basis fits also feature four preferred shaft tolerances, they are different in that they include h11, h9, h7 and h6 (Madsen & David 357). The sliding fit is one kind that does not offer freely running. The sliding tolerance leaves a small clearances hence achieves accurate guiding of rotating shafts. As such, moving parts are able to turn freely, move with ease and also locate accurately. The sliding fit can be used in different applications such as clutch disks, crankshaft journals, sliding gears, pistons used in hydraulic machines and the rods along which bearings slide (Richards 147).
The interference fit is used where the parts that are assembled require a combination of important accuracy of location, great alignment and rigidity. In this regard, the assembled parts are cold pressed so that they align closely and are rigid. This kind of tolerance is used in the hubs of clutch disks and bearing bushings. On the other hand, close clearance fits are used a combination of fit accuracy and smaller clearances is required. This allows for accurate location when machines are running at moderate speeds as well as journal pressures. Some applications of this fit include machine tool spindles, the general fits in shafts, regulator bearings and sliding rods (Richards 147).
Works cited
Booker, J Raines, M. and Swift, K. Designing Capable and Reliable Products. Oxford: Butterworth Heinemann, 2001. Print.
Joglekar, Anand. Statistical Methods for Six Sigma: In R & D and Manufacturing. Hoboken: John Wiley & Sons, 2003. Print.
Madsen, David A, and David P. Madsen. Engineering Drawing & Design. Clifton Park, NY: Delmar, Cengage Learning, 2012. Print.
Pena-Rodriguez, Manuel E. Statistical Process Control for the Fda-Regulated Industry. , 2013. Print.
Porter, David. Overview of Design for Manufacturing and Assembly (DFMA). Crystal Engineering Corp. Web. 25 Dec. 2014 from http://www.calpoly.edu/~fowen/me428/ Design%20for%20Manual%20Assembly%20Lecture%20Rev%204.pdf
Richards, Keith. Design engineer’s handbook. Ann Arbor. CRC Press. 2012. Print.
Stienstra, David. Introduction to Design for (Cost Effective) Assembly and Manufacturing. Web. 25 Dec. 2014 from http://me.gatech.edu/files/capstone/L071ME4182DFA
Thompson, James R. Empirical Model Building: Data, Models, and Reality. Hoboken, N.J: John Wiley & Sons, 2011. Print.
Viswanadham, N. Analysis of Manufacturing Enterprises: An Approach to Leveraging Value Delivery Processes for Competitive Advantage. Boston: Kluwer Academic, 2000. Print.
Webber, Larry, and Michael Wallace. Quality Control for Dummies. Hoboken: John Wiley & Sons, Inc, 2011. Print.
