MANUFACTURING ENGINEERING PRACTICES IN METAL PRODUCTS MANUFACTURING IN GHANA(Font Size 14 & Times New Roman)
Sackey, S.M1. and Frimpong, S.A2. (Font Size 12 & Times New Roman & Bold)
1Mechanical Engineering Department, Kwame Nkrumah University of Science and Technology, Ghana.
2Mechanical Engineering Department, Kumasi Polytechnic, Ghana.(Font Size 12 & Times New RomanItalics)
1
Abstract(Font Size 10 & Times New Roman)
Since the first industrial revolution, manufacturing has progressively employed a series subtractive, additive, continuous, net-shape and other processes to realize products. This paper discusses manufacturing engineering and related practices in industries in Ghana involved in metal fabrications. In the study the practice of the principles of manufacturing engineering is investigated using a questionnaire administered at selected metal processing industries in three major cities. The results suggest that these functions are being practiced to various degrees in the firms studied, with production facilities capable of metal forming, fabrication and machining, although the general levels of technology and automation employed are very low. Systems for process planning, process improvements, quality control, tooling design and shop-floor production engineering activities are in place in some firms, albeit, in rudimentary forms; and application of computer aided systems in design and manufacturing is likewise low, all of which may explain why general product innovation and new product introduction levels are very low in the metal products manufacturing sector. (Font Size 10 & Times New Roman)
Keywords: Metal, products, manufacturing, engineering,Ghana (Font Size 10 & Times New Roman)
The full paper including referencing should not exceed 12 pages
1.0 INTRODUCTION (BLOCK LETTERS Font Size 12 & Times New Roman & Bold)
1.1 Background and Functions of Manufacturing Engineering (Font Size 12 & Times New Roman & Bold)
Manufacturing engineering involves, in the main, process planning and tooling design. Process planning translates product design information into the process steps and instructions to manufacture the product efficiently and effectively. The outcome of process planning could be in terms of routings, which specify operation sequences, work centres, tooling and fixtures; operation plans, which typically provide more detailed, step-by-step work instructions including dimensions related to individual operations, machining parameters, set-up instructions, quality assurance checkpoints, and manufacturing drawings to define the partfor assembly planning. Applying these principles makes it far more likely that a product will meet the original design specifications and will be made in time at the estimated cost. Pertinentissues discussed in the literaturebearing on manufacturing engineering include: creation of diversified products by modularity design (Baldwin and Kim, 2000), Flexible Manufacturing Systems (Xu et al, 2013), in which the authors sought to establish that,given the right conditions, enterprises can create product and manufacturing diversity through component flexibility, control flexibility and mixed flexibility.
But the evolution of product design must address the link between design for manufacture (DFM) and design for assembly (DFA). This interface is the starting point for integrated product design and manufacturing management (Gunasekaran and Yusuf, 2002).
Problem Statement
Manufacturing issues involved in multi-product realisation must also be addressed (Sheheryar andChang, 2014) as well as issues ofintegration of design and manufacturing explored by Xue-Feng et al (2013), who obtained results which showed that implementing a product line based on Design for Manufacture and Assembly principles could help improve productivity and relieve bottle-neck situations in manufacturing systems. However, few works address the manufacturing/design interface from a systematically holistic perspective, implying that the literature has yet to explore in detail the interaction between product design and manufacturing engineering and management from an integral perspective (Ulrich and Ellison, 2009).Involving manufacturing engineers in design also fosters innovations to existing products, which are a significant driver and contribution to the build-up of demand for products. Marin-Garcia J.A. et al (2011)and Sen and Ghandforoush (2011), point out that “innovations can be considered to occur successfully at two different levels: Breakthrough (or Radical or High) and Incremental innovation. Radical innovation most commonly involves significant changes in a product or process. It is usually driven either by technology or design, and may sometimes incorporate a new invention”.
An industry survey of manufacturing engineering practices of Ghanaian firms in the metal fabrications sector could help bring to light the extent to which this vital support function is being performed and help identify inherent problems relating to manufacturing engineering. This could help inspire needed actions towards improved performance.
Despite the above, the heart of manufacturing engineering is process planning and tooling design. The former, which has now advanced into Computer Aided Process Planning (CAPP), translates product design information into the process steps and instructions to manufacture the product efficiently and effectively. Its outcome could be in terms of routings, which specify operation sequences, work centres, tooling and fixtures; operation plans, which typically provide more detailed, step-by-step work instructions including dimensions related to individual operations, machining parameters, set-up instructions, manufacturing drawings to define the part for assembly planning and quality assurance checkpoints, such as are supported by Deming’s (2000), framework for quality and productivity improvement, which promotes continuous improvement and getting things right the first time. Small-group employee-participation programmes sprang up in manufacturing industries in Japan as a result of Deming’s philosophy.
There is the need to test the above concepts and survey the manufacturing engineering support function as a whole in Ghana. Such an industry survey of manufacturing engineering practices of Ghanaian firms in the metal fabrications sector could help bring to light the extent to which this vital support function is being performed and help identify inherent problems relating to manufacturing engineering. This could help inspire needed actions towards improved performance.
1.2 Aim and Objectives
The aim of this workis to assess improvements of engineering nature in the metal fabrications sector of Ghanaian industry. The objectives are to:
- investigate the application of manufacturing engineering principles in the metal processing sector of Ghanaian industry, and
- Identify problems, if any, which hamper the application of these principles in the sector.
LITERATURE REVIEW
The Computer Aided Process Planning (CAPP), translates product design information into the process steps and instructions to manufacture the product efficiently and effectively. Its outcome could be in terms of routings, which specify operation sequences, work centres, tooling and fixtures; operation plans, which typically provide more detailed, step-by-step work instructions including dimensions related to individual operations, machining parameters, set-up instructions, manufacturing drawings to define the part for assembly planning and quality assurance checkpoints, such as are supported by Deming’s (2000), framework for quality and productivity improvement, which promotes continuous improvement and getting things right the first time. Small-group employee-participation programmes sprang up in manufacturing industries in Japan as a result of Deming’s philosophy.
2.0 RESEARCH METHODOLOGY
The population of registered firms in Accra, Tema and Kumasi needs to be given.
The industries selected for the study are located in Accra, Tema and Kumasi. This is so because most industrial activity in Ghana is concentrated mainly in those three centres.
The survey method was used to gather data on manufacturing engineering practices in selected metal processing industries in the country. These industries fall into one of several categories. Owing to this, ‘Stratified Random Sampling’ was used in selecting the sampling units to form a sampling frame for the investigation.
2.1 Sampling Size
Sampling units employed in the survey include the categories of the National Board for Small-Scale Industries (NBSSI) in which firms with less than 6 staff are classified as micro, firms with between 6 and 29 staff are designated small, firms with 30 to 49 staff are called medium, and firms with more than 50 staff are designated large. The researchers sought to have a broad based spectrum of sampling units, hence a much larger industrial concern (a food and beverage can manufacturer) outside the NBSSI’s categories was also included in the survey. In addition to this five of the firms were classified as large. The rest are either small or medium in size. All the large firms are situated in Accra or Tema. The total number of firms surveyed is 25.
In applying the stratified random sampling approach the first step was to split the population into segments as listed in column 1 of table 1. This divided the population into important categories relevant to the research interest. The second step was to take asimple random sample within each stratum, while ensuring that the segments were mutually exclusive (i.e. every element in the population was assigned to only one segment).
2.2 Data Collection
A structured questionnaire was administered at the premises of the surveyed firms. In most cases the questionnaire was left with the firm and the response collected at a later date, when a meeting was held with personnel in charge of the manufacturing processes. In all, the questionnaire was sent to fifty firms but only twenty five responded favourably, thirteen (13) of them coming from Kumasi, five (5) from Tema, and seven (7) from Accra.
3.0 RESULTS AND DISCUSSION
3.1 Manufactured Product Mix and Quantities
Question one of the questionnaire sought to find out the product mix and their quantities from metal processing industries. Sixty-six (66) products were recorded from all the twenty-five metal processing industries. These products are grouped into categories that reflect their end use and means of manufacturing as shown in table 1 below. Other products are mining & construction machinery, timber processing machines, and furniture products. The significance of the products and their quantities is that they are produced in-house, an evidence that manufacturing is taking place. Creation of products occur through the transformation ofraw.
Table 1 Distribution of metal products and theirquantities among surveyed firms (Font Size 10 & Times New Roman & Italics)
Product / No.of firms / % / Qty.
(Yearly)
Processed food cans / 1 / 4 / 173 000 000
Gas cylinder products / 1 / 4 / 1 356 000
Formed products / 1 / 4 / 43 896
Roofing sheets / 6 / 24 / 3240 tons
Domestic wares / 1 / 4 / 633677 kg
Other metal fabrications / 15 / 60 / 996
materials into finished articles. The efficiency of the transformation process is dependent on the selection of the best process and its parameters to optimize the quality characteristics of the finished products.The significance of the products and their quantities is that they are produced in-house, an evidence that manufacturing is taking place. Creation of products occur through the transformation of raw materials into finished articles. The efficiency of the transformation process is dependent on the selection of the best process, and of process parameters to optimize the quality characteristics of the finished products.
3.2 New Product Introduction
Of the 25 firms, only 1 (4%) responded introducing 2 new products yearly. This suggests that competition is not so keen and as such market analysis surveys to identify consumer needs which wouldtrigger the process to satisfy such needs are not well in place. This could also be an indication that product sales are not so encouraging. This conclusion is drawn in light of the quantities produced monthly which are quiet low (table 1). The economic success of manufacturing companies depends on their ability to identify the needs of customers and to quickly create products that meet these needs. Achieving these goals is principally as much a manufacturing design problem as it is a marketing one.
From the survey innovations made on existing products are rather of the incremental or low type, which Jones describes as the gradual improvement of a product through a series of steps or product variants, most frequently involving small changes to an existing design.
3.3 Computer Systems for Design/Manufacturing
Seventy two percent (72%), i.e. 18, of the selected metal processing firms do not use any computer systems software, for design/manufacturing. This is bad for competitiveness and growth. Computer aided design (CAD) and manufacturing systems accelerate the design process by eliminating artificial barriers between the traditional product design and manufacturing functions. The traditional product development cycle isolates the roles of the designer, the supplier, the manufacturing engineer, and the assembly worker, resulting in increased development/production time and costs in addition and compromising each part’s performance.
To take advantage of the numerous benefits of soft and hardware technologies in the Ghanaian environment, numerical control systems could be retrofitted to existing conventional machine tools. With this approach old machines would not become waste and operators can slowly get used to new technology though their skills would have to be upgraded for this to happen. In deciding on NC retrofit, answers must be found to pertinent
questions on whether the existing conventional machines would be able to withstand the faster operating speeds of NC machines, how backlash and other machine inaccuracies would be accounted for, and whether any major mechanical modifications wouldbe involved.
3.4 Use of Engineering Drawings
An engineering drawing is a vital tool for communicating information in an engineering manufacturing set up. It is used for product design, development, manufacturing and assembly. One would therefore expect that most, if not all, the 25 firms would respond that they always use engineering drawings. However, from survey, 16% of the firms “never” use engineering drawing. Without the use of engineering drawings one wonders how consideration and determination of the sizes, shapes and tolerances of product parts and assemblies could be communicated in the manufacturing set–up. This situation could impact negatively on inspection, quality control, maintenance, tolerances, fits and acceptable standards.Eighty-four percent of firms use engineering drawings for all the above four purposes. This percentage tallies with the sum of percentages of firms that use engineering drawing “sometimes” and “always”, so in absolute terms the figure may not be as high as it appears.
To achieve quality products, and enhance development of concepts for new products the use of engineering drawings should be of prime interest to engineering manufacturing industries.
3.5 Development of Process Plans
As stated in the literature review, process planning translates product design information into the process steps and instructions to manufacture the product efficiently and effectively. This very important manufacturing engineering function is used by 76% of the firms in their operations. However, since 76% of the surveyed firms do not use any computer system/software, or data sheets for design/manufacturing, it is an indication that the development of the process plans is made manually. Manual process planning is based on a manufacturing engineer’s experience and knowledge of production facilities, equipment, processes, and tooling and their capabilities. In this approach, parts are classified into families and standardized process plans are developed for these part families. Whenever a new part is called for, the process plan for that family would be manually retrieved, marked-up and retyped. This does not improve quality in planning, but rather may account for the low rate of new product introduction observed earlier because the process requires a lot of labour and high manufacturing lead-time. To introduce a new product means process planning activities such as interpretation of product design data, selection of manufacturing processes and machine tools, selection of cutting tools, determination of setup requirements, sequencing of operations, determination of the production tolerances etc., would have to be done manually for all the parts of the product each time the need arises. This is the bane of the Ghanaian metal processing industry regarding the introduction of new products. However, the wide usage of process plans (76%) is a healthy indication that specifications of product parts, machining parameters, step-by-step work instructions, including dimensions related to individual operations, are in use to enhance productquality and facilitate manufacturing and assembly.
3.6 Tooling Design
One of the key functions of manufacturing engineeringis tool design/ modification, and tooling design and specification. From the responses 92% of firms design tooling in-house. The responsibility for this falls on Machinists (4 firms), Blacksmiths (1 firm), the Technical Director (1 firm), Engineers/Supervisors (6 firms), the technical department in consultation with user department (1 firm), Production Managers (2 firms), Workshop Managers/Sectional Heads (6 firms) who have a range of qualifications such as BSc. Mechanical Engineering, Mechanical Engineering Technician Certificate and Basic Education Certificate. Eighty-four percent of the firms surveyed produce jigs and fixtures frequently in-house as well as Go- and No-Go gauges and material handling equipment. Significantly,this shows that a major manufacturing engineering function is being practiced in metal processing industries in Ghana, albeit at a somewhat low level
(Figures 1).
3.7 Evolution of Product Designs