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The major goals of FMS automation in manufacture are to integrate various operations to improve productivity, increase product quality and uniformity, minimise cycle times and effort and reduce labour costs.
Design for Manufacture
1. SUMMARY
Few developments in the history of manufacture have had a more significant impact than robots and computers. The use of them covers a broad range of applications, including computer aided design, material handling, assembly, automated inspection, testing of products and manufacturing processes.
In this report, we will discuss on the design for manufacture of motor heatsink products and its supplied components which are critical in the motor and drive industry. A machining layout will be drawn for manufacturing of grooves of the heatsink. A corresponding cell layout of the plant will also be drawn for the all assembly and processes. Finally, a discussion on the available commercial software evaluation will be carried out for such a design of manufacture for motor heatsink.
2. INTRODUCTION
Flexible manufacturing system (FMS) is a framework that includes every aspect of the engineering manufacturing process, from the initial design stage through to the more important fabrication and assembly stages, with an aim to making the manufacture of the product suitable to represent all aspects of the product's life-cycle. FMS may involve minimising materials cost, or even selecting a process to achieve a particular surface finish. However, minimising cost over the product life-cycle is generally considered as the most important objective of FMS.
The cost reductions can be achieved through a 'fine tuning' process, component by component, after the product has been designed. The key to this method is through applying product simplification, often by analysis using design for assembly. Alternatively, large changes to the product's fundamental structure can have massive impacts on the product's cost. But such large changes are best treated during design, rather than after the design is relatively complete.
In a standard linear manual design process, a product is usually designed and detailed before the manufacturing cost is estimated. Unfortunately, by that point it is too late to improve the costing: the opportunity to consider different design ideas and alternatives is lost.
Some companies implement FMS but do not consider the entire product life cycle. This is generally because they have not found it necessary in the past to do so while remaining profitable companies. However, the times are changing for product assembly and production. And it will become a fundamental business requirement for companies to address whole product life cycles with FMS.
3. REPORT: TASKS
3.1 SUITABLE MATERIAL FOR BASE HEATSINK
There are two types of materials that can be classified under metallic non-ferrous and aesthetically pleasing. The two materials are aluminium and copper. Optimum designed aluminium heatsinks have a higher thermal performance than copper-based heatsinks. Aluminium is as good as copper for a uniform heat source. Copper heatsinks might be advantages depending on the heat source size, i.e. when the heat source becomes smaller. At higher motor velocities, percentage difference between copper and aluminium becomes more pronounced.
It is widely known that copper conducts heat better than aluminum, but aluminum convects heat better than copper. This is the main reason why copper at higher air velocities performs better, because it can get the heat from die to fin faster than aluminum. If the air velocity is kept low, then the aluminum performs better, because it's more efficient at convection. The main important factor in a motor heatsink is its natural ability to dissipate the largest amount of heat in the shortest possible time. The material is one factor that plays an important role in its ability. Aluminium is the more popular choice for a vast majority of heatsinks Aluminum is an excellent conductor of heat, and considered cheaper than copper. Almost all heatsinks are made of metal because of the need of such conduction property. It is all about displacing and transfer of heat from the running motor to the heatsink material. The suitable material must have the ability to absorb a lot of heat, quickly. Copper seems to be more better than aluminium in this ability.
According to the heatsink industry, aluminum has been the primary material for interconnects on motors because of its conducting powers. But there is also a slow movement towards copper interconnects replacing the aluminum ones. Copper is indeed a better conductor than aluminum. So, why aren't more motor heatsinks made out of copper? The main reason for aluminum to be chosen as the ideal material for the past 30 years is it is cheaper than copper The use of aluminium for bulk mass production of heatsinks saves cost tremendously compared to the amount one would need to make a pure copper heatsink. Thus, aluminum is the most suitable material to be used for base. There are also hybrid-type heatsinks that have the best of both worlds by combining the two, e.g. the base the motor is made out of aluminium, and the rest of the heatsink is made of copper.
3.2 TYPES OF MACHINE TOOLS REQUIRED FOR BASE
Most manufacturers today use sophisticated machining tools and equipment to perform high-speed, ultra precise machining, manufacturing, and processing for the motor industry with an emphasis on heat sinks and other thermal products. They are equipped to have the capabilities to produce complex components and assemblies. With such cutting edge technology, mass production of motor heatsinks is easily achieved with reduced cost, production and assembly time.
The key to delivering quality heatsink products is having the right machine to produce the right part for the right feature. This may require a number of secondary operations on the heatsink parts, such as the grooving portion (discussed in later sections). The final objective is to be able to produce a quality heatsink part in high volumes
To properly manufacture a fabricated component like heat sink, it takes more than just equipment. Even though the CNC's, lathes, deburring, stamping, punching and inspection equipment can perform most of the bulk of the work, it is important to know what other processes are available to perform a machining task. This knowledge base of information will be discussed in the following sections so that the best and most cost effective heatsink part can be manufactured. The following are operation/machine tools required to produce a heatsink base:
Cuttoff tools such as slitting saws, saws, cold saws, bandsaws or abrasive cutoff saws.
Micro-slicing tools such as tension blade saws and angle cutters.
Turning machines for heatsink part formation, grooving operations.
CNC machining using tool punch and hydraulic bender.
Grinding machine for grinding and finishing operations.
Drilling machine to drill motor hole through heatsink.
33 SHOCK ABSORBING/DAMPING MATERIAL FOR MOTOR/HEATSINK
The most suitable shock absorbing material is a mounting pad made of plastic. The heatsink normally do not attach to the pad. The motor is actually attached to a plastic housing, which is then attached to the pad. The pad with housing should be is designed such a way as not to restrict airflow to and from the motor and to heatsink. The plastic casing should resemble the size and shape of motor giving it a maximum allowance of +/- 3mm.
34 DESIGN FOR MACHINE LAYOUT
The item is motor heatsink and the portion of the heatsink to be machined is the grooving part which is produced on a machine assembly line. An acceptable number of machines, tooling requirements and operation are assumed as tabulated in Tables 1-1 below.
|
Stages |
Operation (for one set) |
Machine or process |
No. of M/Cs or tool sets required |
|
A |
CNC punch inner and outer base plates for heatsink |
CNC punch |
1 |
|
B |
Remove metal components from punched sheet and deburr |
Grinding and finishing equipment |
1 |
|
C |
Bend all metal sections required for 1 heatsink case |
CNC Hydraulic bender |
1 |
|
D |
Drilling of hole for motor intrusion |
Drilling m/c with drill bit size 35 dia and counterbore 26.25 dia |
1 |
|
E |
Cutting of grooves along heatsink plate case |
Turning m/c with abrasive cutoff saws |
1 |
Fig. 1-2 shows the machine sequence and layout of the entire machining operation of heatsink and grooves. This sequence is the representation of the machine layout per machining line and is referenced to the Table 1-1.
35 DESIGN FOR PRODUCTION CELL LAYOUT
Table 1-3 shows the complete manufacturing for motor, heatsink and base mounting pad. It also shows the assembling of the finished and supplied components to form the complete artefact. The number of machines required for each stage to assemble one complete artefact is drawn out The table 3 below shows the figures for such a production output of 2 cases per line per day.
|
Stages |
Operation (for one set) |
Machine or process |
No. of M/Cs, tool sets or stations required |
|
A |
CNC punch inner and outer base plates for heatsink |
CNC punch |
1 |
|
B |
Remove metal components from punched sheet and deburr |
Grinding and finishing equipment |
1 |
|
C |
Bend all metal sections required for 1 heatsink case |
CNC Hydraulic bender |
1 |
|
D |
Drilling of hole for motor intrusion |
Drilling m/c with drill bit size 35 dia and counterbore 26.25 dia |
1 |
|
E |
Cutting of grooves along heatsink plate case |
Turning m/c with abrasive cutoff saws |
1 |
|
F |
Inspection of motor - fully assembled from sub-contractor |
Motor test rig and magnifying glass for visual inspection |
1 |
|
G |
Assemble of all components |
Basic hand tools or robots |
1 |
|
H |
Insert motor and heatsink into position |
Basic hand tools or robots |
1 |
|
I |
Inspection of assembled artefact part |
Magnifying glass only |
1 |
|
J |
Pack into boxes and onto pallet |
Boxes, tape, pallets and shrink wrap |
- |
The above table indicates that stages A-E comprises of the machining operations for heatsink. Stages F-J are the manual assembly operations of the motor, heatsink and mounting pad. The motor is assumed to be fully assembled and are bought from a third-party sub-contractor. Quality inspections are also done for the motor and after assembly at this stage. The assembly of finished components can be done either by a manual worker or by highly sophisticated robots such as the articulated robotic arms found in most manufacturing companies
Production Cell Manufacturing Layout
A diagrammatic plan representation of the manufacturing (production) layout is produced as illustrated in Fig. 1-4. There are 3 production lines instead of 1 to facilitate quicker outputs and meet the daily production targets that would satisfy production and company profits. This is based on the production sequences collected and tabulated on Table 1-3. The production cell layout includes:
3 manual or robot articulated assembly cells
5 manual or robot assembly stations for each assembly cell
3 sections of parts storage for each line dedicated to the machining process lines
Each machining process line for heatsink consist of 5 stations
A total of 3 lines each for both the machining process and assembly
An holding area for vendor storage to store surplus incoming parts such as motors and accessories from vendors and suppliers
A defective area for holding Quality flagged cases
10' by 10' staging area for pallets with wrapped fully assembled and tested motor heatsinks
Legend:
The diagram clearly shows the dashed lines with arrows indicating the flow of process (or production route) from each cell. The stages from 'A' to 'J' signifies what is happening at each point of process and assembly. There are 2 two-way conveyer belts between the each of the three assembly and inspection lines. The production floor has sufficient exit points to provide smooth flow of materials, visitors and workers at all times. For more details of the specific operations for each stage can be referred to Tables 1-3.
3.6 AN EVALUATION REPORT ON VAI SYSTEM 2000 FOR MANUFACTURING
(COMMERCIAL AVAILABLE SOFTWARE FOR FMS SOLUTIONS)
VAI system 2000's manufacturing applications provides the need to control all aspects of flexible manufacturing business. System 2000 covers work orders, material processing, production scheduling, material costing, shop floor control and job tracking. The flexibility of software application offers an exact fit for any manufacturing environment.
Flexible manufacturing orders can be produced as per make to order or stock and they can be entered as planned manufacturing orders. Make to order direct material transactions can be entered directly through the sales order entry process where an order can be personalized to the customer's exact requirements. Using the product configurator, the desired order can be customized using the many features and options.
The System 2000 orders process allows the user to create work orders for finished assembly or sub-assembly items for make to stock transactions. With its unlimited bills of material level, each work created order will display the subassemblies, components and item availability. When there is a shortage of components, System 2000 will automatically suggest immediate purchase orders where necessary The flexible manufacturing order will print the routing operations, number and type of components required, as well as any other necessary instructions. The production scheduling system will immediately alert the manufacturing crew (user) to over scheduling orders and produce the relevant graphs, displays, and reports. The user can view the schedule according to department, work center, and/or machine. The user may also choose to include demand from firm orders, quotes, and pre-planned manufacturing orders. There are a variety of inquiries displaying the status of the work order, open, pending and completed operations, together with the complete production history which includes actual against standard cost analysis. Data collection for shop floor is also fully supported. In relation to the material issues and labor times, the System 2000 easily calculates the actual cost and close the work order.
System 2000's Flexible Manufacturing Module also provides for Material Requirements Planning (MRP). The MRP system is tightly combined with the Customer Orders, Inventory, Sales Analysis (Forecasting), Purchasing, and Manufacturing modules of System 2000, and is sensitive to company and location (plant) specific criteria.
MRP analyzes the existing on-hand position of an item, open purchase orders, open manufacturing orders (including planned, stock, and custom orders), open commitments (open customer orders, future orders, and standing orders), the sales forecast, and then produces a balance.
This analysis can be viewed on-line daily, weekly, or monthly by selecting the appropriate option. Complete pegging is supported allowing the user to view critical data such as when purchase orders are due, when manufacturing orders are due to be completed, and the actual customer orders making up the commitments of an item.
Combining our powerful customer service, inventory management, purchasing, and financial applications with System 2000's manufacturing capabilities creates the elements for success in any discrete or process manufacturing environment.
SYSTEM 2000 MANUFACTURING FEATURES*
|
|
|
*The above table is courtesy of Vormittag Associates Inc.
4. CONCLUSION
A methodology for design of manufacture has been developed above for the fabricating of a mechanical component such as the motor/heatsink using various machining methods. The mass production of the motor and heatsink are represented with a logical diagrammatic layout of a suitable production cell plant. This plant will be able to satisfy all the manufacturing requirements and operation for 365 production days per year. All the use of this design and manufacturing skills has achieved the overall understanding of the concepts of design for manufacture and flexible manufacturing systems.
5. DISCUSSION
The discussion on the flexible manufacturing software 2000 system by Vormittag Associates Inc. is seen as an important tool for quick and easy improvement of any design for manufacture processes. It posses a design challenge for any heatsink manufacturers to implement an efficient fully integrated system for material tracking, inventory checking, bill of material monitoring, material cost control, assembly run-out time, flow of materials to and from the production floor and lines, etc. This system could save plenty of costs and reduce waste, hence, increases the material performance and the overall product infrastructure. The implementation of System 2000 for manufacturing into the company work flow would help to tremendously reduce the overall parts count and the logistics of assembly optimised to minimise cost, reduce complexity and maximise productivity.
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