Comparison Of Different Manufacturing Systems Information Technology Essay

An integrated shop floor layout which structured based on flexible cellular manufacturing system is introduced in an interactive flash type game format to illustrate the benefits of an automated flexible cellular manufacturing system. The proposed shop floor layout is a part of lean manufacturing system and the catalyst of the shop floor is based on Kanban. The products of the layout is limited to three types of brackets for simplicity of demonstration and based on client’s order specifications, the game itself would decide of the cells setup, machining arrangements, work in progress and finally the statistics process control. The objective of the game is to deliver the order in a just in time strategy to the client to earn clients satisfaction and to have a provision of future investment and kaizen for developing the shop floor for more production in a more efficient technique.

The manufacture of products in the present industrial world requires the combined and synchronized efforts of people, machinery and equipment. Hence, a manufacturing system is defined as a combination of humans, machinery and equipments that are bound by a common material and information flow. The materials input to a manufacturing system are the raw materials as well as the information (in the form of customer demand for the required products). The outputs of a manufacturing system are the finished goods that enter the inventory. [1]

Supply Chain

The Supply Chain (SC) consists of all the processes and connections from suppliers to feed the customer. It involves the common terms of materials, information and coordination from suppliers and manufacturers to distributers and as a result to customers through Supply Chain Management (SCM).

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The Supply Chain is the connection which provides the path which supplying raw material could be converted into end-user desired products/ services. Depending on size, type and other specifications of order the Chain size and managements varies. The main purpose is not only to follow the path from order to end-user, but also to control the flow of processes through the system.

In the context of an integrated computer-based management system like ERP software, many ERP vendors claim that the Supply Chain Management is part of ERP solution that provides higher efficiency and more services to benefit the customers through a better organization of main and related activities.

Figure 1 : The scope of Supply Chain Management (Houlihan 1985)

The important role of Supply Chain Management in providing good services is undeniable since the framework of integrated information from raw material, finance and many other activities from supplier to customer is depending on it.

Shop floor layouts

Generally there are three main types of productions, the first of which is mass production, where large numbers of products are made in great quantity. The second type of production is batch production, where a great variety of products are produced in small volume, this is currently the most dominant form of manufacturing and accounts for approximately 80% of manufacturing around the world. The third and final production type is one-off production, where an individual product is produced as required by an individual customer. The selection of product type depends on manufacturing product and requirements of process. Since the manufacturing product chosen is assorted brackets, batch production would be the best option because it allows great variety of products in small volumes.

Batch production passes through the various manufacturing operations as defined by the process plan. However, for setting up a single process plan or production line, it is necessary to identify all the different equipment required to manufacture the product. The main equipment required to produce assorted brackets are:

Cutting machine

Bending machine

Drilling machine

Lathing Machine

In batch production the set-up times, machining times and queuing times vary depending on shop floor layout.

Assembly Line layout

Figure 2: Line layout (Flow line layout)

This layout is used when batch quantities are high or when the product produced varies slightly in form.

Assembly Line layout (or flow line layout) is traditionally used in industries where batch quantities are high or parts produced either vary slightly in form or regularly use the same sequence of work centers and tooling. The resources are laid out in the order of usage and machine loads and outputs are well balanced to minimize stockpiling of WIP between work-stations.

This form of workshop organization is normally associated with a quick turn-around and small set-up times and costs in relation to overall manufacturing costs. It is viewed as being the ideal type of layout in which to run a batch manufacturing facility.

Functional layout

Work centers are grouped together according to function or type as shown in figure 3. Each group or section specializes in only one part of the process.

Figure 3: Functional layoutCellular layout

Work centers are organized on the basis of parts being produced. Group of machines are brought together into cells so that a single cell can manufacture all components of a part.

Figure 4: Product focused, single piece flow, pull production system

Selection of shop floor layout again depends on the manufacturing product. Since the selected product varies considerably in shape line layout can be ruled out. Function layout has the advantage of being flexible and can easily cope with design changes, but it has some key disadvantages which lead to transportation delays, stock pile ups and bad product quality. However, cellular layout was developed to overcome many of the key disadvantages of functional layout.

Figure 5: Cellular manufacturing shop floor layout

Cellular manufacturing is a model for a shop floor layout and has become a fundamental part of lean manufacturing systems that aids manufacturing companies produce variety of products for their customers with as little waste as possible. [2]

In Cellular Manufacturing system, the equipments and workstations are arranged in a well-organized sequence that allows materials and components to move smoothly. For example, if the process for a particular product requires cutting, followed by drilling and finishing, the cell would include the equipments for performing all those steps, arranged in that order. [2] It manufactures products from start to finish in a single process flow with minimal waiting time that also reduces transportation delays. This smooth and free flow of components in cellular manufacturing produces products ‘Just in Time’ (JIT).

Flexible Manufacturing system

A flexible manufacturing system is an integrated manufacturing system of computer-controlled machine tools, transportation and handling systems under the control of a larger computer. Flexibility is attained by having an overall system of control that directs the functions of both the computer-controlled machine tools and the handling systems. These computer systems are designed to be programmed or grouped easily with other devices to be able to allow fast and economical changes in manufacturing process, enabling quick responses to the market changes and allowing mass customization of products.

A flexible manufacturing cell consists of two or more CNC machines, along with a computer cell and a robot. The cell computer is interfaced with the microprocessors of the CNC machines and the robot. The cell controller balances the work load, part scheduling, and controls the flow of materials. The cell robot performs tool changing and maintenance functions that includes: chip removal and inspection of (CNC) tools for either breakage or expressive wear. [3]

Figure 6: Flexible manufacturing cells

Comparison of Different Manufacturing Systems

After analyzing the different manufacturing systems it was found that the assembly line layout is a much simpler and faster process. Although it is not a flexible system, introducing new type of designs and production processes to the system is very difficult (Table 1). While the Flexible Manufacturing System is a much reliable process and produces high-quality parts due to its automated control system. Although it is a very complicated manufacturing system, the parts must be position precisely and timing is necessary to produce a component which can cause problems and slows down the process (Table 2).

Advantages and Disadvantages of Linear (Assembly Line Layout) Manufacturing Process:

Advantages

Disadvantages:

Improved worker expertise

Inflexible, difficult to modify a design or production process

The time taken to produce a product is shorter.

All products produced on one production line will be identical or very similar

The possibility of human error and differences is reduced.

Introducing variety to satisfy individual tastes is difficult

Reduced labor costs, production rate increases

Some variety such as finishes and decorations can only be applied at the end of production line

The Cellular Manufacturing System allows a continuous and smooth production from the start of a single process flow to the end, because of the reduced transport or setup time, or downtime. Although it requires a high capital investment because of the increased number of machines necessary for each cell and the required space for expansion and relocation.

Advantages and Disadvantages of Flexible Manufacturing Process:

Advantages

Disadvantages:

Quick and low cost

Limited capability to adapt to varying products

Low direct labour cost due to reduction in number of workers

Substantial pre-planning activity

Reduced inventory, due to the precise planning and programming

Extremely expensive

Reliable and good quality due to its automated control system

Technological problems of precisely positioning parts and timing is necessary to process a component

Low cost per unit of output due to the high productivity

Complicated manufacturing systems

Savings from the indirect labor, due to reduced errors, modifications, and repairs

Advantages and Disadvantages of (Group Technology) Cellular Manufacturing Process

Advantages

Disadvantages:

Reduces Lead times, setup times, downtime and cycle times

high capital investment

Reduces Work-in-process inventory

Labour resistance (need for cross training and flexibility)

Reduces Wastage of raw materials

Relocation and multiple Equipment cost

Simplifies production scheduling

Tooling/Support

Increases value-added activity of each worker

Reduces part movement and inventories

Increase productivity and quality performance

Finding Part Families

Most of the cellular manufacturing systems are designed to produce any number of associated work pieces. Part family grouping procedures are used for categorizing groups of parts that are similar to one another. Since components of a part family share many qualities, generally software-directed change is all a cellular manufacturing system requires to switch from producing one type of part to another. [4]

JIT is a Japanese philosophy behind there international success in manufacturing market. It has three very simple goals to only produce necessary components or products; at the right quantity; and at precise time they are required. This means products move through manufacturing process one piece at a time and at the rate it’s required. This prevents stock pile up of non-moving products that have already been produced at a cost but are not generating any income because they are piled up in storage facility.JIT attempts to remove all waste, waste in a JIT process is defined as anything other than minimum amount required. It also exposes problems and forces people to solve them through a process of continuous improvements (KAIZEN).

KAIZEN is Japanese term for higher standards in quality and waste reduction through small but continuous improvements. It aims to reduce production cost, defects, work in progress inventories and other waste. Kaizen involves everyone from the chief executive to lower level workers which makes excellent relations between employees and the heads of the company as they work together to achieve a common goal.

Pull or Push System?

The pull and push systems describe the flow and movement of products from raw material to production and customer. The terms are widely used in marketing strategies, so that for some products the market need would identifies the number of orders. In general, the consumer/ customer pulls the products that they need, while the companies pushes their products to sell to customers. In supply chain and marketing both strategic have been used.

In lean and just in Time (JIT) manufacturing system, which is invented by Japanese manufacturing companies, a signaling system which is based on pull strategy is used. The Japanese term is “Kanban”, which means “signal”. Implementation of Kanban system in arrangement of the machinery and work in progress in shop floor layouts will benefit towards Lean manufacturing.

In shop floors working based on Kanban, the machines are connected like a chain, when one finishes its duty, it will send a signal to the previous machine to hand over the second piece. Therefore, the cycle time comparing to the push system will decrease dramatically. Also it is much easier to do the quality check and stop the process in terms of having defects. Finding defects and do required maintenance and having a better team work are also a part of utilization of Kanban.

A good example of Kanban, is the arrangement of products in organized supermarkets. In each section only part of the product is placed for consumer, and the rest is stored to save space in supermarket. When the basket of product is finished, it is a signal for the clerks to fill the basket from the stored products.

Kanban production systems and cellular manufacturing systems are closely related, as a cellular manufacturing layout is typically a requirement for achieving a Kanban system. Kanban system enables the cellular manufacturing layout to significantly reduce the inventory and allows a manufacturing company to produce the products Just-in Time. [5]

Combining CMS and FMS

Cellular manufacturing system (CMS) itself is the arrangement of the manufacturing machinery in cell blocks in an efficient and right order depending on product and value added activities to increase the productivity of the production line. However CMS could be enhanced by integrating it with Flexible Manufacturing System (FMS). In general, combining the two systems would be the first step towards automation and the resultant will benefit the application of CMS concept in an FMS strategy. The combination of the two systems would have the following advantages:

Easy to process large volume of information in CMS (decomposed manufacturing system)

Robotic arms and Automated Guided Vehicles (AGV) are used as material-handling carries, which in some cases the service of these carriers may be limited to one cell

Easy to control and manage the machinery and facilities in CMs compared to functional manufacturing, due to size limit of cells

Grouping some of the operations like forging and heat treatment due to technological compulsions in the system

Products proposal

The products of the shop floor layout are limited to three types of brackets which are L, C and circular for simplicity of demonstration. Based on order specifications the FCMS layout will be automatically adjusted to lead the order based on order delivery deadline or the best possible lead time based on the maximum production capacity. The proposed layout is one of the most efficient layouts that combines the advantages of both CMS and FMS including the Kanban system, and the quality of the products are reasonably accurate due to existence of SPCs in the system.

The Game

The Flash (simulation type) interactive instructive game demonstrates the processes and activities involved in a Cellular Manufacturing system. A screenshot of the game ‘in process’ is shown below:

The above manufacturing shop floor is capable of producing three types of brackets, ‘L’ brackets, ‘C’ brackets and circular brackets with two different types of materials, Aluminium and Plastic depending on the ‘Stock Order’ by a company.

There are 12 Cells in the shop floor having 3 machines in each cell. The machines include: Cutting, Drilling, Bending and Lathe machines. Each cell contains 3 workers, one in charge for each machine.

When an Order arrives, depending on the quantity of brackets required, minimum number of cells are used based on the given lead time. There are three rows of cells for manufacturing of the three types of brackets. Maximum of 25 brackets can be produced by one row of cells in 1 day.

The manufacturing system uses KANBAN ‘pull’ method in order to produce brackets Just-in Time. The raw materials are departed according to the sum of machining time, set-up time and the non-value added time of each cell so that they enters the cell just when the previous product is manufactured and leaves the cell.

Each finished product (bracket) is passed through Statistical Process Control (SPC) unit for quality assurance in order to analyse the geometry of the brackets. In case, a problem is detected by the Quality control unit, the supervisor reports the same to the workers immediately (Green light turns Yellow). However, if the problem is a technical one (that the worker cannot solve) due to a fault in a machine, then the technician is called for help (Yellow light turns Red). Raw materials do not enter the cell until the machine is fixed by the technician. However, a technical fault in one cell does not disturb the process or productivity of other cells.

Also, since it is a Flexible Cellular Manufacturing System, in case the raw materials are wasted and more stock is required under the same (given) lead time, an un-used cell can be manually turned ‘on’ for operation, which would make up for the raw materials lost (or defective brackets) without affecting the ongoing processes. Therefore, unlike any other manufacturing system, if a machine breaks down (and requires to be repaired), the Flexible Cellular Manufacturing System have the ability to maintain the rate of productivity and satisfy the lead time with negligible additional expenses.

Each finished product eventually enters the inventory, and the number of each type of brackets is incremented and recorded with the total cash flow that increments $10 for each bracket. The manager makes sure the company receives the exact number (and type of) brackets as per the order.

This manufacturing system is also capable of handling multiple Orders at a time (provided they are possible in terms of lead time along with the rate of productivity per day) by adding the total number of brackets for each Order all together and splitting the stock once they reach the inventory.

Conclusion

The proposed products for the shop floor layout are L, C and circular brackets. After analyzing different manufacturing systems, and evaluating the advantages and disadvantages of the most efficient systems for implementing Kanban in the shop floor layout, it is clear that using a combined system of Cellular and Flexible manufacturing systems (FCMS) is one of the best possibilities to reach the maximum production capacity, better work environment, reduced time of value added and non-value added activities.

For illustrating the processes involved in a Flexible Cellular Manufacturing System, an interactive flash simulation-type game had been created in Macromedia Flash CS4, which demonstrates the production of three different types of brackets according to various different ‘Orders’ by a company. The game aided in understanding the concept of a cellular manufacturing system using a variety of practical state of affairs involved in a shop floor, including the duties of worker, supervisor, technician, etc. The flash game also illustrated that a downtime in a Flexible Cellular Manufacturing System does not affect the ongoing processes or the rate of productivity, and can even cover up for any defective brackets within the given lead time in order to produce brackets Just-in-Time despite any technical problems in a cell.