How to make a Nut and Bolt in the Workshop

Title

Nut and Bolt

Objective

To manufacture a nut and bolt arrangement

Apparatus/Material

·       Ø3mm x 100mm Rod

·       Ø8 x 1.25 Nuts

·       Tap and Die set(Die)

·       Hammer

·       Hacksaw

·       File

Introduction

          A nut is a type of fastener with a threaded hole. Nuts are almost always used opposite a mating bolt to fasten a stack of parts together. The two partners are kept together by a combination of their threads’ friction, a slight stretch of the bolt, and compression of the parts. The most common shape of bolt head is hexagonal, six sides give a good granularity of angles for a tool to approach from (good in tight spots), but more (and smaller) corners would be vulnerable to being rounded off. Other specialized shapes exist for certain needs, such as wing nuts for finger adjustment and captive nuts for inaccessible areas.

Procedure

          First, we took the metal rod and cut a 105mm long piece from it. After that we removed the small workpieces on both corners of the rod till the total length become 100mm, by using a file and make sure the corners are flat and clean.  Then we measured and marked two points, which is 30mm from one corner and 8mm from the other corner. After that we made 30mm and 8mm nut threads from both corners by using the tap and die set. For that we used a bench vise to hold the rod steadily. After making the threads we put the nut into the thread which is 8mm long. To keep the nut fasten, we knocked to the corner of the rod to make it sealed, using a hammer. Finally, we put the second nut on the other side and fastened.

Discussion

Problems Faced and Solutions

           We faced some common problems while cutting the rod, sharpening the corners and making the thread such as suffocating when cutting and suffocating when using the tap and die set to make the thread. It wasn’t too easy to make the thread using those tap and die sets available at the workshop. Some of them are not tightened and we had to tight them before using. When we are cutting the rod, hacksaw started to suffocate in the rod and as a solution we put some oil on it. After that It was easier than without oil. Tap and die set was rusted and it was so hard to make the thread using it. We had to put oil on it too. After making the thread I had to fasten the nut which is in the 8mm thread. For that I had to knock on the rod using a hammer and while doing it, I faced multiple problems. When I am knocking on the rod, sometimes I knocked on the nut accidently and it damaged the nut. While knocking the rod I had to use the bench vise to hold the rod without moving. Correct method is to place the rod in the edge of the bench vise, but I placed it in the middle accidently. Because of that the rot bended from the middle. So, I had to knock slightly with a hammer on the bended point and make it straight again. These are the main problems I faced during the workshop.

Possible Errors

There were only few possible errors. Most of them are measuring errors while taking the measurements of the rod. Other errors were very small errors that can ignore such as thread gauges.

Possible Hazards

          There were lots of possible hazards that could happened during this workshop. As an example, using the hammer and hacksaw is very dangerous. Luckily, we didn’t face any accidents because of the well explained instructions and guides given by the instructors.

Schematic Diagram

What is meant by M8x1.25 thread?

M8 is an 8mm thread and 1.25 is the pitch (distance from one thread crest to the other in millimeters).

Methods of cutting threads

·       Single-point threading

An operation that uses single-point tool to produce a thread form on a cylinder or cone. The tool moves linearly while the precise rotation of the workpiece determines the lead of the thread.

·       Helical Broaching

Method that uses a specific tool geometry and toolpath to position rapidly, broach the thread in a single half-turn, and then retract rapidly, shortening the cycle time and consuming less energy.

·       Threading with EDM

Internal threads can be Electrical Discharge Machined  (EDM) into hard materials using a sinker style machine.

Methods of Fastening Bolt Head

·       Torque Control Tightening

Controlling the torque which a fastener is tightened to is the most popular means of controlling preload.

·       Angle controlled Tightening

          This method has been applied for use with power wrenches, the bolt being tightened to a predetermined angle beyond the elastic range and results in a small variation in the preload due, in part, to the yield stress tolerance.

·       Heat Tightening

Heat tightening utilizes the thermal expansion characteristics of the bolt. The bolt is heated and expands: the nut is indexed (using the angle of turn method) and the system allowed to cool.

Method of manufacturing Nut and Bolt in mass scale

          In manufacturing nut and bolt in mass scale, there are few main steps that includes in the method.

1.    Heat Treatment – This step is performed to increase the durability of the screw or bolt.

There are two operations within heat treatment:

v Hardening: Here, the fasteners are heated to a high temperature and dipped into a cooling media and that hardens the nut and bolt.

v Tempering: This step is to reduce the excess hardness/brittleness of the fastener.

2.    Surface Finishing – This step includes operations that are performed to alter the surface of the bolt or screw.

Surface finishing can include:

v Knurling: A lathe is used to create crossed, angled, or straight lines into the metal.

v Burnishing/Reaming: A tool is passed along the body pf the fastener in a sliding motion.

v Grinding: To remove imperfections from the screw to make it flat.

3.    Thread Forming and Rolling – These steps are used to make the thread of bolts and screws for many applications.  

4.    Protective Coating – The last step involves coating the screws and bolts with a protective coating which prevents fasteners from rust and corrosion.

After all these steps they are sent to test hardness levels, threading accuracy, impact and tensile strength, torque levels, coating thickness, and mating fit.

Conclusion

          Overall, we had a good idea about the workshop equipment’s and good experience about working in a good manner and carefully without making any mistakes and unwanted accidents.

References

Google.lk. (2018). cutting thread using tap and die - Google Search. [online] Available at: https://www.google.lk/search?q=cutting+thread+using+tap+and+die&rlz=1C1CHWL_enLK806LK806&source=lnms&tbm=isch&sa=X&ved=0ahUKEwig8rqFzLncAhWMuI8KHYYBAGsQ_AUICigB&biw=1536&bih=683#imgrc=x8eFfuZ14XdEuM: [Accessed 25 Jul. 2018].

Google.lk. (2018). cutting thread using tap and die - Google Search. [online] Available at: https://www.google.lk/search?q=cutting+thread+using+tap+and+die&rlz=1C1CHWL_enLK806LK806&source=lnms&tbm=isch&sa=X&ved=0ahUKEwig8rqFzLncAhWMuI8KHYYBAGsQ_AUICigB&biw=1536&bih=683#imgrc=x8eFfuZ14XdEuM: [Accessed 25 Jul. 2018].

Google.lk. (2018). cutting thread using tap and die - Google Search. [online] Available at: https://www.google.lk/search?q=cutting+thread+using+tap+and+die&rlz=1C1CHWL_enLK806LK806&source=lnms&tbm=isch&sa=X&ved=0ahUKEwig8rqFzLncAhWMuI8KHYYBAGsQ_AUICigB&biw=1536&bih=683#imgrc=x8eFfuZ14XdEuM: [Accessed 25 Jul. 2018].

Boltscience.com. (2018). Methods of Tightening Threaded Fasteners. [online] Available at: http://www.boltscience.com/pages/tighten.htm [Accessed 30 Jul. 2018].

Norwood. (2018). The Manufacturing Processes of Bolts, Screws, and Fasteners – Part II. [online] Available at: https://norwoodscrewmachine.com/blog/manufacturing-processes-bolts-screws-fasteners-part-ii/ [Accessed 30 Jul. 2018].