Excess Material Of Part 3 Two Technicians example essay topic

ABSTRACT In this project we used the primavera program to show the relationship between the activities in a chart form. We have also applied the primavera to level the project resources, which include labor and machines. An output for the data of the project before and after leveling is included in the report. Introduction In this project we chose to simulate the production of a mold that produces plastic toilet flush tanks. Our data was obtained from El A meen for Plastics Company. In order to obtain the necessary data we went to the factory in Al-Gabba l Al-Ass far in Kalyubeya.

There we met with the engineer in charge who did his part in explaining to us in detail the different functions of the various mold parts. All the activities, their duration's and precedence relations are described below. Also a detailed description of the workstations and the team members are listed below. We intended to use the PERT model for our calculation but since the primavera can only read one duration for each activity we have calculated the expected time and inserted it as the duration of each activity. Procedure of Manufacturing an Injection Mold for Flush-Tanks To produce a plastic flush-tank we need to manufacture an injection mold that will later be fixed on a plastic injection machine. This mold can cost up to 1,500,000 LE according to its quality.

A high quality mold can produce up to 2,000,000 shots (flush-tanks), which means that every flush-tank will have a fixed cost regarding the cost of the mold of less than one pound. Manufacturing such a mold requires skilled engineers and technicians who can successfully work in a group atmosphere. In contrast to mass production methods a mold is produced only once. Every part of its components needs universal knowledge of engineering techniques to be produced. So it is not astonishing to know that manufacturing such a mold can take up to two and a half years of which half o them are spent in manual surface finishing.

The mold material is tool steel. It consists of a cavity, holders for the parts containing the cavity, a cooling system, an ejection system and holders for fixation on the machine. This mold consists of about 80 different parts including bolts, washers, and different types of guides. However we can divide the mold into 8 major parts which are: 1) - Part one is a locating flange used to place the mold in the right position on the machine in order to allow the injection head to fulfil its task, injecting the molten plastic into the mold, correctly. 2) - Part two has a double function which is a mean of fixation on the machine and holder for part three. 3) - Part three is the female part of the cavity.

It is the most important part because of its high level of precision in order to give the definitions of the outer surface. It is also the most expensive one because of its complex design, the high surface hardness required and the very long period of time required manufacturing it. 4) - Part four is the male part of the cavity, it is the second most important part of the mold because of its complex designs and the difficulty in manufacturing it. However its surface finish is lower than part 3 because it gives the inner details of the product which are not seen by the customer. 5) - Part five is a multifunctional one it serves as a holder of parts four and six, it includes the cooling system from part four and it also includes the ejection holds.

It is one of the largest parts of the mold. 6) - Part six is the ejection plate, which is used for ejecting the flush-tank right after solidification. It has to be smooth to minimize friction with parts four and five. This part needs to be replaced several times during the life cycle of the mold due to its intentional lower hardness to prevent damaging parts three, four and five which are more expensive and harder to replace. 7) - Part seven is the holder of the ejection pins which are fixed with part six, it moves on the connecting guides of parts five and eight to push part six and hence eject the produced flush-tanks 8) - Part eight serves as a mean of fixation on the machine. Description of the Workshop I - The workshop is divided into nine different workstations.

1- The first workstation is a universal milling machine, which has a capacity of cutting ingots up to 750 Kg. The operator is a highly skilled technician who should be experienced enough in material cutting processes. Mathematical knowledge is not necessarily required to operate such a machine. 2- The second workstation is a universal CNC milling machine. CNC stands for Computer Numerically Controlled. Such a machine makes the process of cutting required shapes much easier than the normal operating ones.

Precision up to 0.001 mm can be normally achieved. Special cutting tools which, are normally composed of tungsten carbide alloys are used in order to maintain dimensional accuracy as long possible. However the operator on such a machine must be a highly sophisticated engineer. He must insure that the work piece is rigidly fixed on the machine to prevent any kinds of vibrations and deformations of the supports. He must have a high mathematical knowledge in order to design the required CNC programs, which will describe every path of the tool on the surface of the work piece. 3- The third workstation consists of three lathe machines.

These machines are used to manufacture cylindrical parts. These machines require the least skilled technicians. 4- The fourth workstation consists of a furnace, which makes the heat treatments required for manufacturing the several parts. This workstation also contains the basin required for coating the parts electrostatically with chrome. The operator of such a workstation must be an engineer who has a good knowledge about metals and alloys and their different phases.

5- The fifth workstation is specialized in welding. A skilled technician who has a good knowledge in the several kinds of welding methods is the operator of this workstation. 6- The sixth workstation is a sawing machine, which is used to cut long raw materials (especially rods) which are then manufactured on the lathe machine. 7- The seventh workstation is the section concerned with the manual surface finishing of the parts and the manual assembling and disassembling of the different parts.

The workers of this workstation are more likely to get paid more than any other worker or technician though they seem to be less important than others. They must have over than 20 years of experience as they provide us with the final dimension with their bare hands. For example the final surface finishing of the female part of the cavity may take up to 60 days of continuous effort of two workers in order to get the final dimensions and the mirror like surface finishing. 8- The eighth workstation is a basic drilling machine, which is operated by a normal worker in order to make inaccurate holes like the ones required for the holders.

9- The ninth workstation is a grinding machine, which is used to surface finish flat objects like the settings (described by the activities). This grinding machine can be operated by a moderate skilled technician. II - The members of the workshop are: 1- A material engineer who takes care of operating the CNC machine as well as the heat treatment workstation and making the designs for the mold in general. He is also responsible for designing the programs for the CNC machine. 2- Two highly skilled technicians, who take care of assisting the engineer in operating the CNC machine, operating the universal milling machine, taking care of the welding required, operating the lathe machines and operating the grinding machine. They must be experienced and have some engineering capabilities like understanding complex drawings.

3- Two workers for the manual surface finishing and the manual assembling and disassembling of molds (see requirements in workstation 7) 4- Normal workers who are responsible for assisting all the members of the workshop. They are able to operate the sawing and the basic drilling machines. These workers are available in large numbers and hence do not represent a limitation in resources. Note: There is also a board of directors and salesmen who are only involved in the first couple of activities and are therefore not included in the resources.

Description of the Activities 10) Market survey: In order to insure that the product is going to be successful, a market survey should be done. This will allow us to know our production planning. Three salesmen will be sent to the market (Cairo, Giza, and Alexandria). It will take them from 15 to 25 days to have a good perception of the demand of the market and to meet with important dealers and customers of the product.

20) Discussion of results: Managers from different departments have to meet with the three salesmen to discuss their results. They will have to make a feasibility study, production and marketing strategy. These studies will take from 30 to 50 days, because in order to reach a final decision, banks and consulting agencies must be deliberated. Also there will have to be a lot of meetings before reaching the final decision.

30) Draft design of product: After taking the decision of producing the flush-tank, an engineer must design the first draft of the product. It would take from 4 to 10 days in order to complete the specified design. 40) Manufacturing of a model: A model of the first draft design will be manufactured out of wood on the CNC machine. It will take from 15 to 40 days to produce this model.

The fluctuation of time is due to the surface finish quality required by the manager. If a rough draft is desired, only 15 days will be enough to achieve that. If on the other hand, an exact model is required, it could take up to 40 days for obtaining a good surface finish which will need a longer period of time on the CNC milling machine and extensive manual finishing. This activity will need an engineer and a technician.

35) - Preparing a simple CNC Program to produce the model: After completing the design an engineer who has a good knowledge of math will write a CNC program to produce the model. It will take from 20-30 days, as it needs a lot of calculations. A formula has to be obtained for every surface. The time variance depends upon the mathematical knowledge of the engineer.

This activity is done on workstation 2.50) - Investigating the shape of the model: The manager, design engineer and a representative from the marketing department will have to meet to investigate the produced shape and gather comments and suggestions to improve the design. It will take from 2-4 days depending on the amount of adjustments required. 60) Second market survey on model: The three salesmen will take the model and make another survey, which will take from 5-10 days to be completed. 70) Making last adjustments to the design of the product: The design engineer will get feedback from the salesmen and the managers in order to make the last adjustments to the design of the product. It will take from him from 2-5 days according to the adjustments he will have to make. 80) Designing the injection mold: The mold will be designed after reaching the final design of the product.

Two engineers will have to draw the forty different parts of the mold on AutoCAD. The different sections of each part must also be drawn, so it will take them from 20-30 days to complete these drawings depending on the complexity of the mold. 90) Purchasing of raw materials: As the raw material has to be purchased from abroad an engineer will have to contact the supplier and demand the required ingots, which are made of tool steel. First, a letter of credit must be opened and then the ingots will be shipped; delay can occur due to complications in the LC or in the shipping process or in customs. Thus, the activity will take from 45-70 days. The ingots will be purchased according to the design.

99) - Designing special CNC machining tools: Due to the extreme depths of the cavity and the complexity of the shape required, the tools needed in manufacturing the mold can not be found in the standard series of companies. So the tools must be specially ordered from specialized companies abroad. After designing the mold the engineer will also design these special tools. If these designs cannot be manufactured by the company adjustments to the design must be made to meet the company's ability. It will take from 20 to 26 days to accomplish these designs by the engineers. 100) Purchasing of special CNC machining tools: After designing the special CNC machining tools, the order has been sent.

Problems in the LC and delivery can lead to some delays. That is why this activity will take a time span from 80 120 days. This activity does not require any human resources from the company. 110) Programs for CNC milling machines: Programs must be written for every setting of every part that will be manufactured on the CNC machine. These programs are very sophisticated due to the complexity of the design, the manufacturing process of tool steel and the mathematics involved in describing the shapes. The time may vary from 80 100 days according to the skills of the engineer.

This programming has to be done after the design of the mold is completed. It is done on workstation two. 120) Preparing ingot of part three for manufacturing: After the arrival of the raw materials and completing the programs of the CNC machine, a technician will transport the ingot of part 3 to workshop. The packaging will be removed and the ingot will be prepared for manufacturing. It will take about half a day, and delays can occur because it is very difficult to handle an ingot without holders. So, it can take up to one whole day.

130) Drilling holes for holders in part # 3: The prepared ingot will be drilled on work-station 8 by a technician. Then holders will be introduced to the ingot. This process will take about half a day. As this process is not complicated no delay is expected. 140) - Rough cutting of excess material of part # 3: After introducing the holders the ingot will go to workstation # 1 where two technicians will have to remove the excess material in order to achieve an approximate contour of the design. This can take from 9-20 days depending on the quality of the tools available in the workshop and fixation problems.

This process is very important to facilitate the work on the CNC milling machine. 150) Manufacturing top plane-setting of part # 3 for the CNC machine: In order to work precisely on the CNC machine a setting has to be manufactured on workstation # 1. This setting must be designed after making the programs for the CNC milling machine, because the engineer who designed the program is the one who must take into account the settings required to fit his program. Also raw materials have to be available. Two technicians will take from 10 20 days in order to complete this setting, which will function as a support and a mean of fixation on the CNC machine. Due to thee complexity of the design (rigidity, very large and smooth surface area, and a very accurate height) several iterations have to be made to achieve the requirements.

The surface area must be grinded on workstation # 9 and the setting must be heat-treated in workstation #4.155) Assembling the top setting with part # 3: After manufacturing the setting and after removing the excess material of part # 3 two technicians will take from 2 - 4 days to assemble part # 3 to the setting by means of bolts and nuts and welding on workstations 5 & 7. The variation in the time is due to the fact that the complexity of the job can only be known through trial and error until the assembly is rigid. 160) Fixation of the assembly on the CNC machine: The same two technicians will transport the assembly to workstation # 2 in order to fix the assembly on the machine table using bolts. This activity may take from half a day up to one whole day depending on the number of trials that have to be done in order to reach the required rigidity at which the assembly is fixed to the machine. This activity depends upon the arrival of the special tools required for the machining process.

170) Rough milling of the desired shape of top of part # 3: An engineer and a technician have to activate the program and survey the automatic milling process to ensure that the milling operation is running smoothly. The cutting tools have to be replaced after certain time intervals. This activity will take from 30 60 days due to the complexity of part # 3. According to the life span of the tools and the problems that may be faced in the process of milling a large variance of time has to be accounted for. 180) Final milling of top of part # 3: After the rough milling of part # 3 a final milling operation has to be done to reach an acceptable surface finish and a pre-final accuracy. This activity may take from 30 60 days due to huge number of iterations that have to be done to achieve the required specifications.

As the engineer has to make trials in order to reach optimum speed and feed that result in the desired surface finish, he cannot pre determine a deterministic time span in which the activity can be completed. 185) Inspection of dimensions of the top plane of part # 3: After the final milling operation the engineer has to check the dimensions achieved by this operation. Normally this will take one day, but practically the desired dimensions can not be obtained as planed in the program. So generally this inspection is followed by one or two iterations on the CNC milling machine according to the variance of dimensions the engineer has found. So it can take up to 10 days. 190) Removal of part # 3 from the CNC milling machine: After ensuring that we achieved the required dimensions 2 technicians have to remove part # 3 with its setting from the CNC machine.

This is followed up by cleaning the machine and preparing it for following operations. This deterministic activity takes half a day. 200) Manufacturing bottom plane-setting of part 3 for the CNC machine: In order to precisely on the CNC machine a setting has to be manufactured on workstation # 1. Due to the complexity of the design (rigidity, very large and smooth surface area, and a very accurate height) several iterations have to be made to achieve the requirements. The surface area must be grinded on work-station # 9 and the setting must be heat-treated in work-station #4.205) Assembling the bottom setting with part # 3: After manufacturing the setting, and removing part # 3 after completing the top plane milling, two technicians will take from 2 - 4 days to assemble part # 3 to the setting by means of bolts and nuts and welding on workstations 5 & 7.210) Fixation of the assembly on the CNC machine: The same two technicians will transport the assembly to workstation # 2 in order to fix the assembly on the machine table using bolts. 220) - Rough milling of bottom of part # 3: An engineer and a technician have to activate the program and survey the automatic milling process to ensure that the milling operation is running smoothly.

This activity will take from 5 10 days as the bottom part of part # 3 is less complex than the top part, also there is less work to be done as there less material to be removed. 230) - Final milling of bottom of part # 3: After the rough milling of bottom of part # 3 a final milling operation has to be done to reach an acceptable surface finish and a pre-final accuracy. This activity may take from 3 5 days due to huge number of iterations that have to be done to achieve the required specifications. This operation takes less time than the top surface because there is less work involved in this surface. 240) - Inspection of dimensions of the bottom plane of part # 3: After the final milling operation the engineer has to check the dimensions achieved by this operation. So it can take up to 3 days.

250) Removal of part # 3 from the CNC milling machine: After ensuring that we achieved the required dimensions 2 technicians have to remove part # 3 with its setting from the CNC machine. 260) - Manufacturing left plane-setting of part 3 for the CNC machine: In order to work precisely on the CNC machine a setting has to be manufactured on workstation # 1. The surface area must be grinded on work-station # 9 and the setting must be heat-treated in work-station #4.265) Assembling the left setting with part # 3: After manufacturing the setting, and removing part # 3 after completing the bottom plane milling, two technicians will take from 2 - 4 days to assemble part # 3 to the setting by means of bolts and nuts and welding on workstations 5 & 7.270) - Fixation of the assembly on the CNC machine: The same two technicians will transport the assembly to workstation # 2 in order to fix the assembly on the machine table using bolts. 280) - Rough milling of left plane of part # 3: An engineer and a technician have to activate the program and survey the automatic milling process to ensure that the milling operation is running smoothly. This activity will take from 3 4 days because the left part of part # 3 is the least complex part. According to the life span of the tools and the problems that may be faced in the process of milling a variance of time has to be accounted for.

290) - Final milling of left part of part # 3: After the rough milling of the left part of part # 3 a final milling operation has to be done to reach an acceptable surface finish and a pre-final accuracy. This activity may take from 1 2 days. This operation takes less time than the bottom surface because there is less work involved in this surface. 300) - Inspection of dimensions of the left plane of part # 3: After the final milling operation the engineer has to check the dimensions achieved by this operation. So it can take up to 2 days. 310) - Removal of part # 3 from the CNC milling machine: After ensuring that we achieved the required dimensions 2 technicians have to remove part # 3 with its setting from the CNC machine.

320) - Manufacturing right plane-setting of part 3 for the CNC machine: In order to work precisely on the CNC machine a setting has to be manufactured on workstation # 1. The surface area must be grinded on work-station # 9 and the setting must be heat-treated in work-station #4.325) Assembling the right setting with part # 3: After manufacturing the setting, and part # 3 after completing the left plane milling, two technicians will take from 2 - 4 days to assemble part # 3 to the setting by means of bolts and nuts and welding on workstations 5 & 7.330) - Fixation of the assembly on the CNC machine: The same two technicians will transport the assembly to workstation # 2 in order to fix the assembly on the machine table using bolts. 340) - Rough milling of right plane of part # 3: An engineer and a technician have to activate the program and survey the automatic milling process to ensure that the milling operation is running smoothly. This activity will take from 3 4 days because the right part of part # 3 is the least complex part.

350) - Final milling of right part of part # 3: After the rough milling of the left part of part # 3 a final milling operation has to be done to reach an acceptable surface finish and a pre-final accuracy. 360) - Inspection of dimensions of the right plane of part # 3: After the final milling operation the engineer has to check the dimensions achieved by this operation. 370) - Removal of part # 3 from the CNC milling machine: After ensuring that we achieved the required dimensions 2 technicians have to remove part # 3 with its setting from the CNC machine. 380) First part of manual finishing of part # 3: This activity can be started after completing the milling operations of the four different sections of part # 3. Then part # 3 is transported to work station # 7 where two highly skilled workers will have to manually smoothen the surface of the part using sand paper, grinding stones and powdered towels to achieve a mirror like surface finish.

This operation will only reach an accuracy of + 0.05 mm to allow minor deformations during the heat treatment process. This activity will take from 25- 45 days because it is impossible to exactly determine how many times the workers have to go over the surface to achieve required accuracy and surface finish. 390) First part of heat treatment of part # 3: After the first part of manual finishing a technician puts part # 3 in a furnace (work station # 4) where it remains for one day (deterministic time). 400) - Preparing ingot of part # 5 for manufacturing: After the arrival of the raw materials and completing the programs of the CNC machine, a technician will transport the ingot of part 5 to workshop. 410) Drilling holes for holders in part 5: The prepared ingot will be drilled on work-station 8 by a technician. 420) - Rough cutting of excess material of part 5: After introducing the holders the ingot will go to workstation # 1 where two technicians will have to remove the excess material in order to achieve an approximate contour of the design.

This can take from 8-12 days depending on the quality of the tools available in the workshop and fixation problems. Note that the rough milling of this part takes less time than part # 3. This is due to the fact that this part is less complex and there is less material to be removed. 430) Manufacturing top plane-setting of part 5 for the CNC machine: In order to work precisely on the CNC machine a setting has to be manufactured on workstation # 1. The surface area must be grinded on work-station # 9 and the setting must be heat-treated in work-station #4.435) Assembling the top setting with part # 5: After manufacturing the setting and after removing the excess material of part # 5 two technicians will take from 2 - 4 days to assemble part # 5 to the setting by means of bolts and nuts and welding on workstations 5 & 7.440) Fixation of the assembly on the CNC machine: The same two technicians will transport the assembly to workstation # 2 in order to fix the assembly on the machine table using bolts. 450) Rough milling of groove (in part # 5) where part # 4 is fixed: An engineer and a technician will supervise this process on workstation # 2.

In this process we achieve an accuracy of +0.1 mm. According to the quality of the cutting tools, the surface finish required and the rigidity of the assembly on the machine, this activity may take from 3 6 days. 460) Rough milling (in part # 5) of contact surface with part # 6: An engineer and a technician will supervise this process on workstation # 2. Note that this activity has no relation with the previous one. But, as the two activities are performed on the same part and cannot be made in parallel one has to proceed the other. It was our choice to choose this sequence.

470) - Rough milling (in part # 5) of contact surface with part # 3: An engineer and a technician will supervise this process on workstation # 2. Same note as in the previous activity applies to this activity. 490) - Preparing ingot of part # 4 for manufacturing: After the arrival of the raw materials and completing the programs of the CNC machine, a technician will transport the ingo of part # 4 to the workshop. 500) Drilling holes for holders in part # 4: The prepared ingot will be drilled on workstation # 8 by a technician.

510) Manufacturing of setting of part # 4 for the CNC machine: In order to work precisely on the CNC machine a setting has to be manufactured on workstation # 1. The surface area must be grinded on work-station # 9 and the setting must be heat-treated in work-station #4.515) Assembling the setting with part # 4: After manufacturing the setting and after drilling the holes of the holders of part # 4 two technicians will take from 2 - 4 days to assemble part # 4 to the setting by means of bolts and nuts and welding on workstations 5 & 7.520) Fixation of the assembly on the CNC machine: The same two technicians will transport the assembly to workstation # 2 in order to fix the assembly on the machine table using bolts. 530) First machining in the section (of part # 4) matching with part # 5: An engineer and a technician will supervise this operation which will take place after fixation of part # 4 on the CNC machine. It will take about 2 - 4 days to achieve an accuracy of +0.1 mm. This variance in time is due to unknown number of iterations to be done.

540) Drilling the cooling holes in part # 4: The same team will do this activity after the first machining is completed. Due to the large depth of the cooling holes the drilling tool may wear out, so this process may take 1 3 days on work station # 2.550) Drilling the fixation holes of part # 4 with part # 5: Also the same team is responsible for this deterministic activity which will take 1 day on workstation # 2.560) Final finishing of section (part # 4) matching with part # 5: The same team will finish milling this section up to the desired dimensions. No iterations are required here because the matching section in part # 5 is the one to be adjusted to fit this part, so it will take about 1 day in workstation # 2.570) - Removal of part # 4 from the CNC milling machine: After ensuring that we achieved the required dimensions 2 technicians have to remove part # 4 with its setting from the CNC machine. This is followed by cleaning the machine and preparing it for following operations. 580) Manual finishing of the section in part # 4 matching with part # 5: Two highly skilled workers will have to manually smoothen the matching surface.

Due to the unknown number of iterations this activity will take from 1 2 days in workstation # 7. This short time is due to the fact that the surface is not as large as the surface of part # 3 which took a much longer time. 600) Finish milling of the groove (part # 5) in which # 4 will be fit: This activity will be done by an engineer and a technician on workstation #2. It will take from 1 4 days. This variation in time is due to the fact that the number of iterations needed to correctly fit part # 4 is unknown. Of course this activity can start after the manual finishing of the section (part # 4) matching in the groove of part # 5 is done.

610) Drill holes (part # 5) for fixation with part # 4: The same team as in the previous activity will take a deterministic of half a day to finish this job on workstation #2.620) - Removal of part # 5 from the CNC milling machine: After ensuring that we achieved the required dimensions 2 technicians have to remove part # 5 with its setting from the CNC machine. 630) Assembling of parts 4 & 5: Two technicians will assemble parts 4 & 5 on workstation # 7. This activity will take from 2 4 days because the process of fitting the two is a rather complex one as they have to exactly and rigidly fixed. 640) Fixation of the assembly on the CNC machine: The same two technicians will transport the assembly to workstation # 2 in order to fix the assembly on the machine table using bolts.

This activity may take from half a day up to one whole.