For instance, the average of seven screws in the original mouse has been reduced to zero with snap fits. The new mouse also requires no assembly adjustments, whereas the average number for previous designs was eight. The total number of assembly operations has decreased from 83 in the old product to 54 in the new mouse.
All these improvements add up to a mouse that is assembled in s, rather than s for the conventional one. Cycle time, too, has been reduced by DFMA. A second development project that adhered to the new methodology was finished in 18 weeks, including the hard-tooling cycle. As part of thc commitment to total customer satisfaction, Motorola has embraced the six-sigma philosophy for product design and manufacturing. It seemed obvious that simpler assembly should result in improved assembly quality.
With these precepts in mind, they set about designing the new generation of vehicular adaptors zS. The portable-products division of Motorola designs and manufactures portable 2-way Handi-Talkie TM radios for the landmobile-radio market. This includes such users as police, firemen and other public-safety services, m addition to the construction and utility fields.
These radios are battery-operated, and are carried about by the user. They also considered that an important part of any design was to benchmark competitors" products as well as their own, At the time. Several of their competitors also offered similar units fo,: their radio products. The results of the redesign efforts were so encouraging that Motorola surveyed several products which had been designed using the DFA methodology to see if there might be a general correlation of assembly efficiency with manufacturing quality.
Fiqur, I9 shows what they found. The defect levels are reported as defects per million parts assembled, which allows J quality evaluation to be made that is independent of the number of parts in the assembly'. Motorola's six-sigma quality goal is 3. Each result in Figure 19 represents a product with an analysed assembly efficiency and a reported quality lew:!
The transmission is a complex product, with approximately parts and 15 model variations. Choose pilot programme Choose test case. Identify team structure. Identify team members. Coordinate training. Have first workshop. Break up into teams. Analyse the existing design for manual assembly. Analyse the teams' redesigns for manual assembly. Teams present results of original design analysis versus redesign analysis.
Prioritize redesign ideas: A, B, C etc. Incorporate all the A and B ideas into one analysis. Assign responsibilities and timing. Even more importantly, the changes resulting from DFA have brought substantial quality improvements. Moreover, the design leadtime has been reduced by one-half, and is expected to be halved again.
Reduced cost and improved manufacturability was reflected in Ford's profits for GM found that there was a large productivity gap between its plant and the Ford plant.
For example, the Ford car had many fewer parts ten in its front bumper compared with in the GM Pontiac , and the Ford parts fitted together more easily.
The GM study found that the level of automation, which was actually much higher in the GM plant, was not a factor in explaining the productivity gap. More recently, General Motors has been releasing details of improvements made to their designs through their own adoption of DFMA principles.
In each case, a considerable reduction in part count has been achieved, resulting in a simpler product. By way of a summary, Figure 20 shows the effect of DFA on part-count reduction taken from published case studies, and Table 7 gives details of other improvements taken from the same case studies.
Average reduction: Quite frequently, it is suggested that, since assembly costs for a particular product form only a small proportion of the total manufacturing costs, there is no point in performing a DFA analysis.
Figure 21 shows the results of one analysis in which the assembly costs were extremely small compared with the material and manufacturing costs. The view is often expressed that DFMA is only worthwhile when the product is manufactured in large quantities.
It could be argued, though, that the use of the DFMA philosophy is even more important when the production quantities are small. This is because, commonly, an initial design is usually not reconsidered for low-volume production. Applying the philosophy 'do it right the first time' becomes even more important, therefore, when the production quantities are small. How many times have we seen an inspection cover fitted with numerous screws.
There is a danger in using design rules because they can guide the designer in the wrong direction. Generally, rules attempt to force the designer to think of more simply shaped parts which are easier to manufacture. This can lead to more complicated product structures, and a resulting increase in total product costs. In addition, m considering novel designs of parts which perform several functions, the designer needs to know what penalties there will be when the rules are not followed.
For these reasons. However, when one design is rated as better than another using D F M A databases, it would almost certainly be rated in the same way using customized databases. Some say that D F M A is only value analysis. It is true that the objectives of DFMA and value analysis are the same. However, it should be realized that D F M A is meant to be applied early in the design cycle, and that value analysis does not give proper attention to the structure of the product and its possible simplification.
Experience has shown that D F M A can make significant improvements even after value analysis has been carried out. Some have referred to this proliferation of acronyms as alphabet soup! Many have even suggested that design for performance is just as important as DFMA. One cannot argue with this. However, D F M A is the subject that has been neglected over the years, while adequate consideration has always been given to the design of a product for performance, appearance etc. The other factors, such as quality and reliability, will follow when proper consideration is given to the manufacture and assembly of the product.
Some say that D F M A leads to products that are more difficult to service. This is absolute nonsense. Experience shows that a product that is easy to assemble is usually easier to disassemble and reassemble. Similarly, when products contain significant electrical mterconnections, the labour involved in wire preparation, harness assembly and installation can far outweigh the time needed for mechanical assembly. Figure 22 shows an example in which enormous savings in assembly time were found to be possible through redesign.
In this instrument, considerable disassembly was needed when it was necessary to change the batteries Figure 23 shows the total assembly and disassembly times during the life of the product, indicating clearly that the designer should be aware of total 'lifecycle costs" during Assembly Time rains is0 r.
Initial Assembly Time Total: 3. Of couse, these lifecycle costs ideally include the cost of recycling. However, as pointed out above, some still claim that design rules or guidelines sometimes called producibility rules developed by them can give similar results. This is not so. In fact, the application of guidelines or qualitative procedures can lead to increased product complexity, because the guidelines or procedures are usually aimed at simplifying the individual component parts.
For example, limiting the number of bends in a sheet-metal part may seem like a good producibility rule, but, in fact, it can lead to an expensive design that incorporates numerous simple sheet-metal parts assembled with a multitude of fasteners.
The resulting product will have poor quality, and will entail larger overheads resulting from a larger inventory, more suppliers, and more record keeping. Rather, the objective should be to utilize the capabilities of the individual manufacturing processes to the fullest extent to keep the product as simple as possible. In spite of all the success stories, the major barrier to DFMA implementation continues to be that of human nature. In the following chapters, the basic components of assembly machines are presented, and the overall performance of assembly systems is discussed.
Finally, detailed analyses of the suitability of parts and products for both manual and automatic assembly are presented. Schwartz, W. Nof, S. Assembly Survey, Assembly, December Society of Manufacturing Engineers , May 8, Munro, S. Terborgh, G. Seering, W. Aron, P. Cyert, R. Boothroyd, G. For this method of assembly, a machine is required for transferring the partly completed assemblies from workstation to workstation, and a means must be provided to ensure that no relative motion exists between the assembly and the workhead or robot while the operation is being carried out.
As the assembly passes from station to station, it is necessary that it be maintained in the required attitude. For this purpose, the assembly is usually built up on a base or work carrier, and the machine is designed to transfer the work carrier from station to station; an example of a typical work carrier is shown in Figure 2. Assembly machines are usually classified according to the system adopted for transferring the work carriers Figure 2.
Thus, an in-line assembly machine is one in which the work carriers are transferred in line along a straight slideway, and a rotary machine is one in which the work carriers move in a circular path. In both types of machine, the transfer of work carriers may be continuous or intermittent. When the operations are completed, the workheads return to their original positions and, again, keep pace with the work carriers. Alternatively, the workheads move in a circular path tangential to the motion of the work carriers.
In either case, the assembly operations are carried out during the period in which the workheads are keeping pace with the work carriers. Continuous-transfer systems have limited application in automatic assembly because the workheads and associated equipment are often heavy and must therefore remain stationary.
It is also difficult to maintain sufficiently accurate alignment between the workheads and work carriers during the operation cycle because both are moving. Continuous-transfer machines are most common in industries such as food processing or cosmetics, where bottles and jars have to be filled with liquids. As the name implies, the work carriers are transferred intermittently, and the workheads remain stationary.
These machines may be termed indexing machines, and typical examples of the rotary and in-line types of indexing machines are shown in Figure 2. With rotary indexing machines, indexing of the table brings the work carriers under the various workheads in turn, and assembly of the product is completed during one revolution of the table. Thus, at the appropriate station, a completed product may be taken off the machine after each index.
The in-line indexing machine works on a similar principle but, in this case, a completed product is removed from the end of the line after each index. With in-line machines, provision must be made for returning the empty work carriers to the beginning of the line. The transfer mechanism on in-line machines is generally one of two types: the shunting work carrier or the beltdriven work carrier.
The shunting work carrier transfer system is shown in Figure 2. In this system, the work carriers have lengths equal to the distance moved during one index.
Positions are available for work carriers at the beginning and end of the assembly line, where no assembly takes place. At the start of the cycle of operations, the work carrier position at the end of the line is vacant. The piston then withdraws, and the completed assembly at the end of the line is removed. The empty work carrier from a previous cycle that has been delivered by the return conveyor is raised into position at the beginning of the assembly line.
Although the system described here operates in the vertical plane, the return of work carriers can also be accomplished in the horizontal plane. In this case, transfer from the assembly line to the return conveyor and vice versa is simpler, but greater floor area is used. In practice, when operating in the horizontal plane, it is more usual to dispense with the rapid return conveyor and to fit further assembly heads and associated transfer equipment in its place Figure 2.
However, this system has the disadvantage that access to the various workheads may be difficult. A further disadvantage with all shunting work carrier systems is that the work carriers themselves must be accurately manufactured. For example, if an error of 0. This error could create serious difficulties in the operation of the workheads.
However, in all in-line transfer machines, it is usual for each work carrier, after transfer, to be finally positioned and locked by a locating plunger before the assembly operation is initiated. The belt-driven work-carrier transfer system is illustrated in Figure 2.
Basically, this machine uses an indexing mechanism that drives a belt or flexible steel band to which the work carriers are attached. The work carriers are spaced to correspond to the distance between the workheads.
Instead of attaching the work carriers rigidly to the belt, it is possible to employ a chain that has attachments to push the work carriers along guides. In this case, the chain index can be arranged to leave the work carriers short of their final position, allowing location plungers to bring them into line with the workheads.
Wheels Automatic Assembly Transfer Systems 23 2. The The The The The The required life of the machine dynamic torque capacity required static torque capacity power source required to drive the mechanism acceleration pattern required accuracy of positioning required from the indexing unit Generally, an increase in the size of a mechanism increases its life.
Experience shows which mechanisms usually have the longest life for given applications; this is discussed later. The dynamic torque capacity is the torque that must be supplied by the indexing unit during the index of a fully loaded machine. The dynamic torque capacity is found by adding the effects of inertia and friction and multiplying by the life factor of the unit, the latter factor being derived from experience with the use of the indexing unit.
The static torque capacity is the sum of the torques produced at the unit by the operation of the workheads. If individual location plungers are employed at each workhead, these plungers are usually designed to withstand the forces applied by the workheads; in such a case, the static torque capacity required from the indexing unit will probably be negligible.
The power required to drive an indexing unit is obtained from the dynamic torque applied to the unit during the machine index. The form of the acceleration curve for the indexing unit may be very important when there is any possibility that a partially completed assembly may be disturbed during the machine index.
A smooth acceleration curve will also reduce the peak dynamic torque and will thus assist the driving motor in maintaining a reasonably constant speed during indexing, thereby increasing the life of the machine.
The accuracy of the indexing required will not be great if locating plungers are employed to perform the final positioning of the work carriers or indexing table. Various indexing mechanisms are available for use on automatic assembly machines; typical examples are given in Figure 2. These mechanisms fall into two principal categories: those that convert intermittent translational motion usually provided by a piston into angular motion by means of a rack and pinion or ratchet and pawl Figure 2.
For all but very low-speed or very small indexing tables, the rack-and-pinion or ratchet-and-pawl mechanisms are unsuitable because they have a tendency to overshoot. To ensure a fairly constant indexing time, if the power source is a pneumatic cylinder, it is usual to underload the cylinder, in which case the accelerations at the beginning and end of the stroke are very high and produce undesirable shocks.
The ratchet-and-pawl mechanism requires a takeup movement and must be fairly robust if it is to have a long life. The weakest point in the mechanism is usually the pawl pin and, if this is not well lubricated, the pawl will stick and indexing will not occur. The Geneva-type indexing mechanism has more general applications in assembly machines, but its cost is higher than the mechanisms described earlier.
However, it has a high peak dynamic torque immediately before and after the reversal from positive to negative acceleration. In its basic form, the Geneva mechanism has a fairly short life, but wear can be compensated for by adjustment of the centers. The weakest point in the mechanism is the indexing pin, but breakages of this part can be averted by careful design and avoidance of undue shock reactions from the assembly machine. A characteristic of the Geneva mechanism is its restriction on the number of stops per revolution.
In a Geneva mechanism, the smaller the number of stops, the greater the adverse mechanical advantage between the driver and the driven members. This results in a high indexing velocity at the center of the indexing movement and gives a very peaked acceleration graph.
On a three-stop Geneva, this peaking becomes very pronounced and, because the mechanical advantage is very high at the center of the movement, the torque applied to the index plate is greatly reduced when it is most required. The solution to these problems results in very large mechanisms relative to the output torque produced. As the number of stops provided by a Geneva mechanism increases, the initial and final accelerations during indexing increase although the peak torque is reduced.
This is due to the increased difficulty in placing the driver center close to the tangent of the indexing slot on the driven member. For a unit running in an oil bath, the clearance between the driver and driven members during the locking movement is approximately 0.
To allow for wear in this region, it is usual to provide a small center-distance adjustment between the two members. The clearance established after adjustment is the main factor governing the indexing accuracy of the unit, and this will generally become less accurate as the number of stops is increased. Because of the limitations in accuracy, it is usual to employ a Geneva mechanism in conjunction with a location plunger; in this way, a relatively cheap and accurate method of indexing is obtained.
The crossover cam type of indexing mechanism shown in Figure 2. Its cost is higher than that of the alternative mechanisms described earlier, and it also has the minor disadvantage of being rather bulky. The acceleration characteristics are not fixed as with other types of indexing mechanisms, but a crossover cam can be designed to give almost any required form of acceleration curve. The normal type of cam is designed to provide a modified trapezoidal form of acceleration curve, resulting in a low peak dynamic torque and fairly low mean torque.
The cam can be designed to give a wide range of stops per revolution of the index plate, and the indexing is inherently accurate. A further advantage is that it always has at least two indexing pins in contact with the cam.
Figure 2. It can be seen that the modified trapezoidal form gives the best pattern for the smoothest operation and lowest peaking. The sine and modified sine both give smooth acceleration, but the peak torque is increased, whereas with the Geneva mechanism, the slight initial shock loading and the peaking at the reversal of the acceleration are clearly evident.
Adapted from Huby, E. Machines are available, however, for which a new cycle of operations can be initiated only when signals indicating that all the previous operations have been completed are received. This is referred to as operator pacing. One basic characteristic common to all the systems described is that a breakdown of any individual workhead will stop the whole machine, and production will cease until the fault has been rectified.
One type of in-line intermittent operator-paced machine, known as a free-transfer or nonsynchronous machine Figure 2. In this design, the spacing of the workstations is such that buffer stocks of assemblies can accumulate between adjacent stations. Each workhead or operator works independently, and the assembly process is initiated by the arrival of a work carrier at the station. The first operation is to lift the work carrier clear of the conveyor and clamp it in position.
Thus, on a free-transfer machine, a fault at any one station will not necessarily prevent the other stations from working. It will be seen later that this can be an important factor when considering the economics of various transfer machines for automatic assembly.
Huby, E. In this feeder Figure. The bowl is usually supported on three or four sets of inclined leaf springs secured to a heavy base. Vibration is applied to the bowl from an electromagnet mounted on the base, and the support system constrains the movement of the bowl so that it has a torsional vibration about its vertical axis, coupled with a linear vertical vibration.
The motion is such that any small portion of the inclined track vibrates along a short, approximately straight path, which is inclined to the horizontal at an angle greater than that of the track. When component parts are placed in the bowl, the effect of the vibratory motion is to cause them to climb up the track to the outlet at the top of the bowl.
Before considering the characteristics of vibratory-bowl feeders, it is necessary to examine the mechanics of vibratory conveying.
For this purpose, it is convenient to deal with the motion of a part on a straight vibrating track that is inclined at a small angle to the horizontal.
The amplitude of vibration a0 and the instantaneous velocity and acceleration of the track may all be resolved in directions parallel and normal to the track. These components will be referred to as parallel and normal motions and will be indicated by the subscripts p and n, respectively. It is assumed in the analysis that the motion of a part of mass mp is independent of its shape and that air resistance is negligible. It is also assumed that there is no tendency for the part to roll down the track.
It is useful to consider the behavior of a part that is placed on a track whose amplitude of vibration is increased gradually from zero. Automatic Feeding and Orienting — Vibratory Feeders 31 the part will remain stationary on the track because the parallel inertia force acting on the part will be too small to overcome the frictional resistance F between the part and the track.
Figure 3. The condition for forward sliding up the track to occur is, therefore, given by combining Equation 3. The limiting condition for forward conveying to occur is given by comparing Equation 3. This can occur only when the normal reaction N between the part and the track becomes zero. From Figure 3. An is the normal track acceleration and gn the normal gravitational acceleration.
The detailed types of motion that may occur in vibratory feeding have been described in the literature . For all conditions, the part starts to slide forward at some instant when the track is nearing the upper limit of its motion. When there is no hopping mode, this forward sliding continues until the track is nearing the lower limit of its motion, at which point the part may remain stationary relative to the track or slide backward until the cycle is complete.
In some cases, the stationary period is followed by a period of backward sliding only or of backward sliding followed by yet another stationary period.
Finally, the forward sliding is followed by a period of backward sliding and then a stationary period to complete the cycle. The modes of conveying are summarized in the following flow diagram: 34 Assembly Automation and Product Design Clearly, a complete analysis of all the possible modes of vibratory conveying is complicated.
Such an analysis has been made  and leads to equations that must be solved numerically. For the purposes of the present discussion, it is considered adequate to describe only the main results of this analysis and the results of some experimental tests. It can be seen that the experimental values for a range of frequencies fall on one line when the factor fvm is used as a measure of the conveying velocity.
This confirms the prediction of the theoretical analysis. One consequence of this result is that, for high conveying velocities and hence high feed rates, it is desirable to use as low a frequency as is practicable. However, because the track accelerations must be kept constant, this result means that there is a corresponding increase in track amplitude.
The mechanical problems of connecting the feeder to a stationary machine imposes a lower limit on the frequency, but some advantages can be gained by lowering the operating frequency of a bowl feeder from the usual 60 Hz to 30 Hz . At first, the velocity of impact as the part lands on the track is small but, as the track acceleration is increased further, the impact velocity also increases until, at some critical value, the part starts to bounce. Under these circumstances, the feeding cycle becomes erratic and unstable, and the theoretical predictions are no longer valid.
From Redford, A. The effect is shown more clearly in Figure 3. For clarity, these theoretical predictions are shown without the supporting experimental evidence. However, it can be seen from the figure that even if conveying can be achieved on the track, the mean conveying velocity will be significantly lower than that around the flat bottom of the bowl.
This means that, in practice, the parts on the track will invariably be pushed along by those at the bottom of the bowl, where they tend to circulate at a greater speed.
During the testing of such orienting devices, parts transported individually along the track may behave correctly. However, when the bowl is filled and a line of parts forms along the track, the parts tend to be forced through the orienting devices by the pressure of those at the bottom of the bowl.
This pressure may often lead to jamming and a general unreliability in operation. The value 0. It can be seen that, for practical values of track acceleration, an increase in friction leads to an increase in conveying velocity; hence, the advantage provided by coating the tracks of bowl feeders with rubber.
Coatings can also reduce the noise level resulting from the motion of the parts, which is often an important consideration. When the bowl is operating properly with no rocking motion, the vertical component of motion an will be the same at every location in the bowl. The magnitude of the horizontal component ap, however, changes with the radial position.
The horizontal component increases linearly with increasing radial position. If the vibration of the base is important, the vibration angle should be determined experimentally by comparing the signals from two accelerometers, one mounted vertically and the other horizontally.
For the present example, the magnitude of the vibration angle at a radial position mm from the bowl center can be found from Equation 3. The conveying velocity of the parts on the inclined track is usually governed by the pushing action of the parts circulating around the bottom of the bowl.
The functional relationship from Equation 3. The dimensionless scales shown at the top and at the right of Figure 3. Then, according to Figure 3. The vibration amplitude can be adjusted while an operator monitors a special decal mounted on the outer rim of the bowl. This decal is used to measure the peak-to-peak amplitude or twice the horizontal amplitude of the vibration at that point.
The correct value of this horizontal amplitude depends on the bowl diameter and is found from geometry. Although parts are apparently conveyed by vibratory motion with an almost constant conveying velocity, this motion is, actually, a combination of a variety of dissimilar smaller motions giving the total effect of smooth movement.
This combination of smaller motions is cyclic and usually repeats with the frequency of the drive. Some of the details of this motion are important in the design of orienting devices used in vibratory-bowl feeders.
The effective length of the hop is the smallest gap in the track that will reject all point masses traveling with this motion. The magnitude of this effective hop can be determined from Figure 3. The scales on the top and right side of Figure 3. Similarly, Figure 3. It should be noted that intensive theoretical and experimental work has been carried out by Jimbo et al.
This change occurs because, for a constant power input, the amplitude of vibration and, hence, the maximum bowl acceleration usually increases as the effective mass of the loaded bowl reduces. It can be deduced from Figure 3. Vibratory-bowl feeders are often used to convey and orient parts for automatic assembly and, because the workheads on an assembly machine are designed to work at a fixed cycle time, the parts can only leave the feeder at a uniform rate.
The change in performance as a feeder gradually empties is referred to as its load sensitivity, and the upper curve in Figure 3. It is of interest to compare this result with the measured changes in bowl acceleration shown in Figure 3. Clearly, when a feeder empties, the feed rate will reduce to zero, but Figure 3. This behavior is considered to be due to the greater velocity of parts in the flat bowl bottom than that on the track; this was described earlier. When the bowl is full, the feed rate depends mainly on the feeding characteristics at the bottom of the bowl, where the general circulation of the parts pushes those on the track.
However, as the bowl empties, leaving mainly those parts that remain on the track, the pushing action ceases, and the feed rate depends only on the conveying velocity on the inclined track, which is generally lower than that on a horizontal surface. This explains the difference in character between the graphs in Figure 3.
The load detector switch is simply a mechanical arm and limit switch that detects when the level of parts in the bottom of the bowl falls below some predetermined level. When closed, the switch activates the secondary feeder and refills the bowl to a predetermined level. This action essentially increases the frequency of refills, reducing the recirculation effect to almost zero. A second solution requires modification to the feeder.
Frequency-response curves for the vibratory-bowl feeder used in the previous experiments are presented in Figure 3. These curves show the effect of changes in the forcing frequency on the bowl acceleration for a constant power input and for various bowl loadings. In these tests, the power input is less than that employed in the test shown in Figure 3. However, it can also be seen that, whereas for a forcing frequency of 50 Hz the frequency used in Great Britain , the maximum bowl acceleration is sensitive to changes in bowl loading, for a forcing frequency of approximately 44 Hz, the bowl acceleration is approximately constant for all bowl loadings.
Under these latter conditions, the load sensitivity would be considerably reduced. Alternatively, it is clear that increasing the spring stiffness of the bowl supports sufficiently would have the effect of shifting the response curves to the right and minimizing the changes in bowl acceleration for a forcing frequency of 50 Hz. The natural frequency of the empty, as-received bowl was approximately 53 Hz, and tests showed that, if this was increased to 61 Hz by increasing the support spring stiffness, the load sensitivity of the feeder was considerably reduced.
The lower curve in Figure 3. It can also be seen, however, that the feed rates have been reduced by stiffening the support springs and, therefore, in order to maintain the higher feed rate, a more powerful drive would be required.
Generally, vibratory-bowl feeders are tuned to a natural frequency only slightly higher than the frequency of the drive; this serves to minimize the power by utilizing the ease of transmission of vibration at or near the natural frequency.
A line of parts is stored in the external feed track and, when the line becomes short, the lower sensor activates the feeder, 46 Assembly Automation and Product Design filling the line up to the level of the upper sensor which, in turn, shuts the feeder off. Some of the more expensive vibratory-bowl feeders use silicon-controlled rectifier SCR drive systems, which can be coupled with accelerometer feedback to maintain a constant amplitude of vibration.
This prevents the mean conveying velocity of the parts from increasing as the bowl empties. A typical spiral elevator is illustrated in Figure 3.
The helical track passes around the outside of a cylindrical tube. This device is not generally used to orient parts because the parts cannot readily be rejected back into the hopper bowl situated at the base of the elevator. Because the mode of conveying for the parts is identical to that obtained with a vibratory-bowl feeder, the results and discussion presented earlier, and the design recommendations made, will also apply to the spiral elevator.
Automatic Feeding and Orienting — Vibratory Feeders 47 3. For this reason, the base of a vibratory-bowl feeder is usually supplied with rubber feet. However, these feet provide the feeder with additional degrees of freedom and, if the bowl and tooling are not dynamically balanced, a rocking motion can be superimposed on the motions of the bowl.
This rocking motion affects the vibration angle at the bowl track so that, in some regions of the track, the vibration angle is increased and, in some regions, it is decreased. This results in erratic behavior of the parts so that, along certain portions of the track, a high conveying velocity occurs while, along others, the parts slow down or even tend to stop.
Recent site activity View All. The design for assembly DFA method has become a widely used way for companies to introduce competitive designs at reduced costs. This text places the consideration and application of automatic assembly in the context of DFA, addressing design for both automated and manual assembly processes.
The author enumerates the components, processes, performance, and comparative economics of several types of automatic assembly systems. To this end, the book includes specific information on equipment such as transfer devices, parts feeders, feed tracks, placing mechanisms, and robots.
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Automatic assembly using special purpose machines. Annual Production Volume and Manufacturing Sophisticated products involves a large individual components and subassemblies. Fall Fall View 1: technology, tool or method used to improve entirely the design and manufacturing process and increase productivity More information. Industrial Robotics. Training Objective Training Objective After watching the program and reviewing this printed material, the viewer will learn the basics of industrial robot technology and how robots are used in a variety of manufacturing More information.Use template. Search this site. Richard Hackman. Incredibly Easy! Warshaw R. Pocket Guide Incredibly Easy! Badaracco Jr. Series Full Series Online Book - by. About Our Events. Russell Boulding. Lamar Blount. Van Horn. Mark A Riddle M. Join Our Club. Our Members. Assembly Automation and Product Design, Geoffrey Boothroyd. Hybrid ment Council, who used DFMA to provide a free "costing service" that gave. Addressing design for automated and manual assembly processes, Assembly Automation and Product Design, Second Edition examines assembly automation in parallel. related research articles, book chapters and information is free to access and ByGeoffrey Boothroyd DownloadPDF MB. Assembly Automation and Product Design, Geoffrey Boothroyd Government works Printed in the United States of America on acid-free paper Downloaded. Assembly Automation and Product Design Second Edition MANUFACTURING ENGINEERING AND MATERIALS PROCESSING A Series of Author: Geoffrey. Product design for manufacture and assembly Geoffrey Boothroyd Design is the However, it was found that automation could only account for one-third of the. [PDF DOWNLOAD] The OCD Workbook: Your Guide to Breaking Free from DOWNLOAD Assembly Automation and Product Design, Second Edition (Manufacturing and Materials Processing) Best Seller EPUB - by Geoffrey Boothroyd. minimize product cost through design and process improvements. Describe how product design has a primary influence concerned only with reducing product assembly cost. – minimizes number of Assembly Automation and Product Design Assembly. G. Boothroyd and P. Dewhurst, Boothroyd Dewhurst, Inc. Boothroyd G. Assembly Automation and Product Design. Файл формата Comparison of Indexing and Free-Transfer Machines Economics of. Design for Automated Assembly of Large and Complex Products: Experiences from a Join for free Download full-text PDF In the book Mechanized Assembly  Geoffrey Boothroyd & A.H Redford studied automatic assembly and. The question is that of whether manufacturability and ease of assembly are more important than automation in improving productivity. Sometimes, these design changes result in considerable delays in the final product release. In each case, a considerable reduction in part count has been achieved, resulting in a simpler product. Fiqur, I9 shows what they found. People resist new ideas and unfamiliar tools, or claim that they have always taken manufacturing into consideration during design. The cam takes up less room than the gearbox arrangement; this allows the driving point to be moved from the end of the carriage assembly towards the middle, reducing torque on the carriage and resulting in a smoother motion. More recently, General Motors has been releasing details of improvements made to their designs through their own adoption of DFMA principles. Then, using a case study, the philosophy of the Design for Manufacture and Assembly DFMA methodology and its application are explained. Figure 18 shows the old and new mice. Only fundamental reasons relating to materials properties are acceptable. Handling uncertainty in the establishment of a design space for the manufacture of a pharmaceutical product. They used D F M A software to compare such factors as assembly times, part counts, assembly operations, labour costs,.