Blanking and Piercing
“When a number of identical components are required blanking and piercing tools can be used to punch holes in and stamp out the sheet metal. The two processes are very similar – the words that are used show which material is to be kept and which is waste (blanking – kept, piercing – waste). Strips of metal are passed between a flat-faced hardened alloy steel punch and a matching ‘die’ hole. The punch is forced through the strip and shears the metal of the die. The whole shape is pressed instantaneously from the strip in one movement. This requires heavy pressure for a short time and the process is often automated. Blanking and piercing operations are often combined in a progression tool.”
My hole punch will carry out a similar process to blanking and piercing, however my hole punch will make just one hole at a time and will not require a large amount of force. Blanking and piercing is more of an industrial process.
Batch Production
It would be intended that my hole punch will be made as a prototype before making many more replicas for batch production. In industry most products are manufactured using batch production methods to speed up the process and to ensure they are identical.
Jigs and fixtures are often used to speed up the production process during manufacture of batch products. They are used to locate the job and to clamp it into place. This means someone does not have to measure and mark out each individual component. The jig is the device which is responsible for locating and holding down the job and the fixture is the device which helps clamp the job.
CAM (computer-aided manufacturing) is another batch production process. This is a more modern method of locating and clamping job and has replaced the need for jigs and fixtures in many applications. CAM involves computer controlled devices which work at high speeds and at a very high accuracy – even the tools on the machines are changed automatically. The main advantage with CAM is that man does not have to aid it in any way, other than switching the machine on and off. Many CAM programmes also enable the user to machine complex shapes. The products made are always identical, of a high quality and very accurate.
If my hole punch was manufactured for batch production, each of my components would need to be able to be made using either jigs and fixtures or computer-aided machines.
Levers and Linkages
- A lever is to increase MECHANICAL ADVANTAGE
- A linkage is a method of linking one lever to another
I need levers and linkages in my hole punch for the following reasons:-
- To hold the components together
- To stop it from falling apart
- To increase mechanical advantage
- To make it look good
Motion
There are four types of motion:
Linear
Reciprocating
Oscillating
Rotary
Metals: Ferrous Metals
There are two types of metals – ferrous and non-ferrous. Ferrous metals contain iron, this means they rust. They tend to be tough and durable. Ferrous metals are used for general purpose jobs.
Below is a list of possible ferrous metals that I could use for hole punch.
After having looked at the characteristics of these ferrous metals, I have decided that mild steel would be an appropriate ferrous metal to use in the making of my hole punch. Due to its very high melting point of over 1600oC, this material is strong and durable and yet it can still be easily welded because once heated it is malleable and ductile. It would be economical to use mild steel because it is a general purpose metal, making it fairly inexpensive. The main disadvantage of mild steel is that it cannot be hardened or tempered. Mild steel is not very light either and this is why a contrasting non-ferrous metal could be used too.
Metals: Non-Ferrous
Non-ferrous metals do not contain iron – this means they do not rust. They tend to be used for more specialised jobs. Non-ferrous metals are not as strong as ferrous metals.
After having looked at the characteristics of these non-ferrous metals, I have decided that aluminium would be an appropriate non-ferrous metal to use in the making of my hole punch, (if appropriate). It is a cheap, light and soft metal which will harden in cold temperatures. Aluminium polishes well, thus creating a good finish to my hole punch. I think it would be an appropriate metal to excessively use because of its weight; my hole punch will be suitable for a key stage 4 student and must be light enough for them to carry. Unfortunately there is not a great amount of aluminium available in the workshop and I would therefore have to keep the amount of aluminium (if any) I use, low.
Investigation for Key Stage 3 Students
It is necessary to carry out an investigation to determine how I should adapt my hole punch to suit the needs of a child between the ages of 11 and 14.
I have decided to take a sample of 12 students (2 males and 2 females from each year group 7, 8 and 9.) This means the sample is representative of age and gender. I shall devise a set of questions will I shall I ask every member of the group – after receiving the results of this investigation I will evaluate my results.
The hole punch will need to be held for up to about 30 seconds at a time – I shall be giving a variety of weights to the group to hold for 30 seconds at arms length to discover how many of the group will succeed the task.
I will also be measuring their handspans so I can adjust the size of the model’s width to ensure it can be hand held.
I will also ask the group their preferred colour.
= Pass = Fail
These results have shown that all the students were capable of holding the 100g, 300g and 700g weights, however on the 1000g weight, one student did not manage to pass the task and by the 1600g weight, three students did not manage to pass the task. I therefore think that my hole punch should not surpass 1000g to ensure that the majority of the keystage 3 students will be able to carry it.
After having measured the group’s handspans, I calculated the average handspan to be 17cm. I must ensure that the width of the hole punch does not exceed this measurement.
The most popular preferred colour for the hole punch was black. I will therefore explore ways in which I can ensure my hole punch will be black.
Specification
After having carried out research into many different topic areas in order to gain ideas and understanding of hole punches, I shall now be writing my product’s specification. I will be categorising each of the hole punch’s individual requirements into five different areas:
- Function
- Aesthetics
- Ergonomics
- Quality & Efficiency
- Reality
Function – meeting design brief requirements
My hole punch must:-
- Be hand-operated
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Be able to punch holes with a diameter of 4mm
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Punch holes through sheet aluminium with a thickness of 1mm
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Produce accurate holes of high quality
Aesthetics – how the product looks
My hole punch must:-
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Look attractive
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Appear professional
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Have a suitable finish
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Be in proportion
Ergonomics – adjusting the product to suit the user
My hole punch must:-
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Weigh less than 1kg
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Have a width less than 170mm
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Have a large handle to decrease the effort needed to punch holes
Quality – ensuring the product is of a high standard
My hole punch must:-
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Balance on a flat surface
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Be securely fixed together
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Be durable and maintainable
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Be easily portable
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Be Safe and simple to use
Reality – being realistic about restrictions and availabilities
My hole punch must:-
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Be completed within time restrictions
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Be affordable
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Be made from the materials available
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Be made using the machines available
Generation of Design Proposals
After having written my design specification, I shall now generate a series of designs which meet the requirements which I have set.
The first five pages of designs look at particular aspects or components of hole punches, I have made comments alongside these sketches to suggest how each idea will work. The next eight pages contain four complete designs of hole punches – the first page of each design explores ideas and explains how each hole punch will function; the second page of each of the four designs is a full colour design drawn to scale.
A short analysis and evaluation of each of the proposed designs accompanies each design and this is featured after all of the sketched pages. A rating has also been allocated to each design to help me decide which proposal I shall be furthering to construction.
Evaluation of Design Ideas
Design Idea 1
This is the only design idea which contains two punches. This will enable the user to create two holes at a time, however, if it was wished that just one hole was created, or the distance between the two punches differed from that on the design, the hole punch could not cater for this.
I think this design idea looks very unprofessional because everything is very bulky and disproportional. The component between the H-block and the handle (in yellow on the diagram) would potentially be a very weak area because of the lack of support it is getting. This problem could be overcome by brazing the two components or using caphead screws or nuts and studs if a temporary fixture was preferred. Because the handle is so big it too will be very heavy, this means that the spring beneath the punch will need to be very strong to support the weight of the handle, but this too will create a problem for the user because a stronger spring will mean that more effort would be needed to punch a hole.
I do not like the look of this design nor do I think it will provide accurate holes. I give this design 4/10.
Design Idea 2
My second design idea uses an unusual construction of levers and linkages to form the handle in order to increase mechanical advantage. This would be the hole punch which would require the least amount of effort to punch a hole through an aluminium sheet.
As well as theoretically working well, I think this hole punch also looks attractive. The metal base plate is sunk into the wooden base by routing a space for it - this makes the design look more professional. There is also a connecting piece of metal between the pillar and the barrel which spaces the hole punch out more.
The only main criticism I have with the hole punch would be lack of space underneath the H-block which will prevent slugs from getting through. However, this is a problem which could be overcome by increasing the distance between the H-block and the metal base plate.
I think this idea looks professional and it has been designed to increase mechanical advantage as much as possible, I rate this 9/10.
Design Idea 3
My third idea is the smallest of my four designs and because of this, without the metal block underneath the base, the product would topple over when pressed. However, because the metal block provides the user with a mechanism which enables the hole punch to be clamped into a vice, the product will be secure when being used.
The drawing does not picture the punch, however this will be similar to the punches used in the other designs. It will use a spring – theoretically, this means the user will not have to lift the handle before pressing it because it will already be up.
The handle is also not fully pictured either, however it will be long to increase mechanical advantage. Because it is flat bar it will be difficult to get a real grip of.
The main disadvantage with this design is the H-block. Unlike my other design ideas, the component has just one slot which is at the bottom of it. This means that the aluminium bar will not be ready positioned and secured in the correct place on the H-block before punching.
Considering aesthetics, ergonomics and theoretical accuracy, I give this design idea 5/10.
Design Idea 4
This design idea relies on the invention of the cam. It is this component which is responsible for pushing the punch to make the hole in the aluminium.
I like this design because of its originality - it is unlike the other three designs because it uses a rotary motion rather than a linear motion. Another reason why I like this design is because the user can see the hole being punched from above.
However, I think that once made, the hole punch may not be efficient enough to produce accurate holes. It too, is very large, thus being heavier and more difficult for students to carry.
The main concern I have with this design is the rod which connects from the cam through the post and to the handle. This could possibly be a very weak component and without consideration this may move from side to side.
I think this is the design that looks the best, however in reality I do not think it would provide me with a satisfactory degree of accuracy. I
give this design idea 6/10.
Components Cutting List
Before shaping each component I will need to cut the materials in order to begin making them.
The table above shows the measurements, materials and quantity of each component. Because of moderations during construction, this is subject to change.
Process Sheets
These process sheets are a step-by-step guide to making each component – they include the order of the tasks, the description of the tasks with measurements, the tool requirements, safety points and estimated and actual times for each task.
Overall Planning
This process sheet is an overall plan of the complete construction of components and fabrication. The plan includes the description of each process, the intended start date, the actual start date, the intended finish date, the actual finish date, the estimated completion time and the actual completion time.
Moderations
During construction, when problems occurred that I had not previously accounted for in my development plan, I made moderations to my hole punch to improve the product and overcome the problem. The table below shows the moderation I made and then the reasoning behind it.
Product Development
After having explored the four proposed design ideas, I have chosen design idea 2 to develop for construction.
Why?
This hole punch would provide the user with a professional looking hole punch which, theoretically, will produce holes of a very high quality. Due to the linkages and levers which make up the handle, there would be a great amount of mechanical advantage which is vital because this would decrease the effort needed by the user to punch a hole into sheet aluminium.
How does the design work?
This hole punch will be spring loaded - the spring will lie between the plunger’s head and the barrel. This spring will hold up the horizontal linkage – because of this, the handle will remain in a diagonal position.
The user will grip the handle and press downwards, pulling the vertical linkages which will also bring the horizontal linkage with it. In turn, this component will press on the plunger, pushing it through the barrel, punching it through the aluminium with its waste going through the hole in the H-block.
How will each component be joined?
The metal plate will be joined to the wooden base with self tapping wood screws which will be fed through countersunk holes in the four corners of the metal plate.
The pillar and the handle block will be joined to the metal plate with screws which will be fed upwards through countersunk holes made in the metal plate and screwed into the components which will have threaded holes.
The H-block will be joined to the metal plate by screws which will feed through clearance holes in the H-block and screw into threaded holes in the metal plate.
The connector will join the pillar to the barrel and this will be done by brazing.
The handle will join with the handle block, the pillar will join with the horizontal linkage, the horizontal linkage will join with the vertical linkages and the vertical linkages will join with the handle with threaded bar with nuts on each end.
Materials and Measurements
Now having planned the design of my hole punch I need to consider the material and measurements of each component. The table below shows the name of the component, the material I will be using, the measurements of it and the reasoning for the choice.
Will My Product Meet the Requirements of My Specification?
Now that both my product has been designed and my speciation has been written, I need to compare the two to ensure that my product will meet the requirements of my specification. Below shows my specification in black – next to each point, in blue writing, I have answered each requirement.
My hole punch must:
Be hand-operated The handle means the hole punch will be hand-operated
Be able to punch holes with a diameter of 4mm The punch will have a diameter of 4mm
Punch holes through sheet aluminium with a thickness of 1mm I cannot test this, but theoretically this should work
Produce accurate holes of high quality The punch will have a rake angle
Look attractive The hole punch is attractive
Appear professional If made to a high standard, the product will appear professional
Have a suitable finish The hole punch will be finished with black spray paint
Be in proportion All of the components are relative in size to each other
Weigh less than 1kg I cannot test this until production, however I will explore ways of decreasing the weight of the hole punch
Have a width less than 170mm The wooden base has a width of 100mm
Have a large handle to decrease the effort needed to punch holes The handle is comparatively large, however I will note any suggestions that will increase this further
Balance on a flat surface The wooden base is large and flat
Be securely fixed together I have planned how each component will be joined and theoretically it should be
Be durable and maintainable I cannot test this, but theoretically it should be
Be easily portable The hole punch will be able to be held and lifted
Be safe and simple to use Every component will be filed and the handle will just need to be pressed for the hole punch to work.
Be completed within time restrictions I will make progress sheets for every component to ensure I complete the task within the allocated time restrictions
Be affordable BDMS and MDF are both cheap materials
Be made from the materials available BDMS and MDF are both available
Be made using the machines available No specialist machines, other than the ones in the workshop will be required
After I have made my final product, I shall again compare my specification to hole punch to ensure the requirements of the specification are met.
Final Product
Evaluation: Does My Product Meet the Requirements of My Specification?
Because my final product has now been constructed I can test my hole punch against my specification. Below shows my specification in black – next to each point, in red writing, I have tested each requirement.
My hole punch must:
Be hand-operated The handle means the hole punch is hand-operated
Be able to punch holes with a diameter of 4mm The punch has a diameter of 4mm and therefore it punches hole with a diameter of 4mm too
Punch holes through sheet aluminium with a thickness of 1mm The product punches hole through sheet aluminium with a thickness of 1mm
Produce accurate holes of high quality The punch has a rake angle to increase the accuracy of the holes, however this is not of high quality as the punched material does not separate completely from the aluminium strip
Look attractive The hole punch looks attractive
Appear professional Because of the evenly painted matt black finish, the product looks professional
Have a suitable finish The hole punch is finished with black spray paint
Be in proportion All of the components are relative in size to each other
Weigh less than 1kg My hole punch weighs less than 1kg
Have a width less than 170mm The wooden base has a width of 100mm
Have a large handle to decrease the effort needed to punch holes During construction I increased the length of the handle even further
Balance on a flat surface The large wooden base allows the hole punch to balance
Be securely fixed together All of the joints are secure and therefore my hole punch stays together
Be durable and maintainable My hole punch is relatively new so I therefore do not know whether it is durable – in theory it should be. The punch is changeable so once blunt it can be replaced.
Be easily portable The hole punch is light enough to be held and lifted
Be safe and simple to use Every component was filed and to operate the hole punch you just need to press the handle
Be completed within time restrictions I completed the task within the time
Be affordable Due to the price of the materials, my product was cheap
Be made from the materials available I used in materials in the workshop only
Be made using the machines available I used the machines and tools in the workshop only
Survey with Key Stage 3 Students
I have devised a set of questions to be answered by the users of the hole punch (key stage 3 students) to help me evaluate the success of the hole punch. I will take the same group of young people as I did to investigate how I should adapt my hole punch ergonomically – this is a representative sample. I will ask each student to rate each aspect of the hole punch from 1 to 5. The table below shows the results of this survey.
1 = least successful 5 = most successful
These results are an accurate way of testing the success of my hole punch because these students will be the users of the product. This is an indication of how I should adapt my product if I was to repeat this project.
The group seemed impressed with the design of the punch and many said it was ‘unusual’ compared to normal hole punches. Although suggesting black as an appropriate colour during the first investigation, some of the group felt black was ‘dull’ but looked ‘professional’. A lot of the students commented on the professionalism of the hole punch and many felt that it looked of a very high quality. When it came to testing the hole punch some students were not satisfied with the shape of the handle saying it ‘did not have any grip’ and was ‘too little in width’. The students all held the product and a lot of the students explained that the hole punch was ‘quite heavy’ and that it ‘should be lighter’. However, everyone was impressed with how ‘little effort it took’ to punch holes in the aluminium strips, but were ‘less than satisfied’ with the quality of the holes which the device produced.
Evaluation
I have now completed the task of designing and constructing a hole punch. I marginally managed to finish in the time period given.
Overall I am generally pleased with my hole punch – I am extremely impressed with the look and design of the product but disappointed with the quality of the holes which are punched using it. I did use the plans which I made earlier on during the production of each component, but made many moderations along the way also; the variety and extent to which I research the given topics helped me tremendously when planning and designing, but it wasn’t until I began making the product when a lot of the realisations occurred.
My hole punch was a lot larger in length and in height than originally intended and although this made the hole punch steadier, it added a great amount of weight to it. If I had more time I would have cut off the wooden base – this would not have altered the mechanical advantage but it would decrease the overall weight by a significant amount.
I am satisfied with the way in which each of the components are joined to one another as all of the joints are very secure. I am especially pleased with the brazed components and this is a permanent fixing which very little time and is virtually unnoticeable. My main criticism with the joints is the nuts and threaded bar as this is a little loose. In every case, the bar could have been made longer and the nuts could then have been tightened further.
BDMS was certainly an appropriate material to make the product with as it is easily shaped, joined and finished. It is heavier than I thought it would be, however no lighter material would have had the qualities which BDMS has.
Every component does it jobs effectively as intended except the punch. The punch does not produce accurate, circular, high quality which is was meant to. I think if this was sharpened more and then hardened and tempered it may produce holes of a better quality. I think to further solve this problem I would secure a form lid above the H block to ensure the aluminium strip does not lift up when being punched.
I could have saved time if I had planned my time better; I found myself constantly queuing for the milling machine and therefore when I did not have other tasks to be doing I was wasting a lot of time. Also, I decided to shorten the vertical linkages after I had drilled, filed and finished them. I could have saved a great amount of time if I had made this decision earlier on.
I have enjoyed making my hole punch and have learnt a lot about planning and designing during the course. If I was to repeat this project I would concentrate more on improving the quality of the holes and concentrate less on aesthetics.
