MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
SHAUFINA JAAFAR ● BUSU SULONG
MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
SHAUFINA JAAFAR ● BUSU SULONG
Politeknik Sultan Haji Ahmad Shah
Published by POLITEKNIK SULTAN HAJI AHMAD SHAH SEMAMBU 25350 KUANTAN
Copyright ©2021, by Politeknik Sultan Haji Ahmad Shah Materials published in this book under the copyright of Polytechnic Sultan Haji Ahmad Shah. All rights reserved. No part of this publication may be reproduced or distributed in any form or by means, electronic, mechanical, photocopying, recording, or otherwise or stored in a database or retrieval system without the prior written permission of the publishers.
TABLE OF CONTENT
Table of Content ------------------------------------------------------------------------------------------------------------- i Abstract ------------------------------------------------------------------------------------------------------------------------ ii Acknowledgement --------------------------------------------------------------------------------------------------------- iii Preface ------------------------------------------------------------------------------------------------------------------------ iv Course Name ----------------------------------------------------------------------------------------------------------------- 1 Course Synopsis ------------------------------------------------------------------------------------------------------------- 1 Course Learning Outcomes ----------------------------------------------------------------------------------------------- 1 Course Content -------------------------------------------------------------------------------------------------------------- 1 Assessment ------------------------------------------------------------------------------------------------------------------- 1 Practical Task Worksheet Drawing (Machining) ---------------------------------------------------------------------- 2 Workshop Rules and Regulations ---------------------------------------------------------------------------------------- 3 1.0
Task Outcome ----------------------------------------------------------------------------------------------------- 4
2.0
Apparatus and Equipment -------------------------------------------------------------------------------------- 4
3.0
Theory --------------------------------------------------------------------------------------------------------------- 4 Introduction --------------------------------------------------------------------------------------------- 4 Process of Grinding ------------------------------------------------------------------------------------ 7 Advantages of Grinding Process -------------------------------------------------------------------- 8 Disadvantages of Grinding Process ---------------------------------------------------------------- 9 Factor affecting the quality of ground workpiece surfaces --------------------------------- 10 Grinding Machine Operation ---------------------------------------------------------------------- 10 Cylindrical Grinding ---------------------------------------------------------------------------------- 11 Surface Grinding -------------------------------------------------------------------------------------- 13
5.0
Procedures to complete the task ---------------------------------------------------------------------------- 15 Procedure Task 1 ------------------------------------------------------------------------------------------------ 15 Procedure Task 2 ------------------------------------------------------------------------------------------------ 18
Practical Dimension & Evaluation Rubric (Task 1) ----------------------------------------------------------------- 22 Practical Dimension & Evaluation Rubric (Task 2) ----------------------------------------------------------------- 23 Report Rubric (Task 1) ---------------------------------------------------------------------------------------------------- 24 Report Rubric (Task 2) ---------------------------------------------------------------------------------------------------- 25 Tutorial Questions --------------------------------------------------------------------------------------------------------- 26 References ------------------------------------------------------------------------------------------------------------------ 28
i
ABSTRACT
Mechanical Workshop Practice 4 coded as DJJ40132 is one of courses planned designed for student of Diploma of Mechanical Engineering. In order to fulfill the Diploma certificate requirements, students need to complete this course during the 5th semester session. This course was conducted practically in workshop. This means that the learning methods for this course is in practical form. For this, the students were given the briefing and demonstration of how to complete the practical task. Then students are allowed to carry out the practical to familiarize the machining operation and enhance the machining skills. The assessment for this course also in a practical form, where students were assigned to complete the task (known as practical task) within the time allocated usually around several weeks. Students also need to produce a report for every task that were assigned. Reports produced must include the procedures, discussion and conclusion related to the objective outcome for the task. eBook DJJ40132 Mechanical Workshop Practice 4 (Machining) was produced designed created initiated as to use a guideline and reference for students to understand the task in the machining work session. This eBook contains all the important information that can be used to understand the task drawing and task procedures, mainly the instruction to operate the machines and perform the cutting and machining process. This eBook also provide the students with marking rubrics and report rubrics. Those rubrics can be used as a guideline for students to perform the practical task and produce a good report. By following the marks distribution in the rubrics, students were given opportunity to score a good mark subsequently gain a good grade for this course. as student can master the report marks as well as the practical tasks given. Thus, it is hoped that eBook DJJ40132 Mechanical Workshop Practice 4 (Machining) can be fully availed by the students in order to master the knowledge and skills of this course.
ii
ACKNOWLEDGEMENT
First of all, we would like to thank our work colleagues, Pn. Masliana binti Idris whose ask and give us opportunity to become a part of team members in producing an eBook of Mechanical Workshop Practice 4 workbook.
Infinite thanks also to other team members; Pn. Aida Haryati binti Muda, Mejar Rizal bin Rohim and En. Mazlan bin Omar for trusting us to complete and produce a machining part in this workbook.
We want to express a million thanks to our head of department of Mechanical Engineering, En. Mohd Khaspi bin Kosnin, Heads of Proggramme, Pn. Zurina Mohamad and En. Muhamad Soffi Manda, whose encourage us to take part as an author of the eBooks of Mechanical Workshop Practice 4 workbook. We want to express gratitude as we are finally able to complete and realizing the eBooks of Mechanical Workshop Practice 4 workbook for the use of Mechanical Engineering Diploma students in Polytechnics.
Best Regards, Busu bin Sulong Nor Shaufina binti Md Jaafar
iii
PREFACE
Mechanical Workshop Practice 4 workbook for machining operation is created for a learning purpose in Diploma of Mechanical Engineering level. This eBook is intended to be a guideline for a student to learn and gain input of knowledge of practical in machining operation.
For this course, the teaching and learning session was carried out practically in a machining workshop. During the practical class, each student was given a piece of task drawing. The task drawing contains an illustration of a project task with all dimensions needed. Students also were given a demonstration by the instructor on how to operate machines, setup the tools on machines and how to perform the machining operation in order to complete the practical task.
However, the last few years restraints with Covid1-19 pandemic have changed the methods of teaching and learning. The restraints of pandemic have forced us to conduct the classes virtually. Thus, the initiative to produce an eBook for Mechanical Workshop Practice 4 course arise to enable the education process to continue without any interruption and delays.
This eBook contains with drawing task, theoretical knowledge of the machining processes and the marking rubrics for the practical works and reports. During the practical session, students were given briefing and demonstration first. Due to the implementing of virtual class, the briefing and demonstration cannot be carried out properly and this requires additional instruction material to be used. The theoretical knowledge included in the eBook, acts as an early briefing to start the practical task. Several textbooks and articles are used to provides references sources for theoretical knowledge of the machining processes. Theoretical knowledge is important as an early exposure and preparation for starting the practical task. While the demonstration of machining operation is replaced by the video demonstration generated by the instructor, purposely for the machining practical task in Mechanical Workshop Practice 4 course.
iv
COURSE INFORMATION
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MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
COURSE NAME Mechanical Workshop Practice 4
COURSE SYNOPSIS MECHANICAL WORKSHOP PRACTICES 4 course allows the students to operate machine tools, precision grinding, CNC machine and able to work in a clean and safe workshop environment.
COURSE LEARNING OUTCOMES Upon completion of this course, students should be able to: 1. CLO1 - Perform high precision machining processes for the surface or cylindrical grinding machine. (P4, PLO5)
2. CLO2 - Construct programs for EDM and CNC machining process using ISO codes or any related machining software. (P5, PLO3)
3. CLO3 - Demonstrate safety procedures in the workshop according to the workshop safety regulation correctly to create a secured environment in an organization while doing practical work and ability to work in team to complete assigned tasks during practical work sessions. (A3, PLO7)
COURSE CONTENT COURSE CONTENT
CLO
TASK
TOPIC
PROJECT 1
MACHINING
1.0 High Precision Machining 1.1 Perform on Surface or Cylindrical Grinding Machine
1
1.2 Follow Standard Operation Procedure (SOP) to keep
3
working area clean and safe.
ASSESSMENT The course is assessed through coursework. i.
Practical Task (P)
- 15%
ii.
Practical Task (P)
- 45%
iii.
Practical Task (A)
- 10%
iv.
Report
- 10%
v.
Report
- 20% 1
PRACTICAL TASK WORKSHEET DRAWING (MACHINING)
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MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
DEPARTMENT OF MECHANICAL ENGINEERING POLYTECHNIC OF SULTAN HAJI AHMAD SHAH DJJ40142 MECHANICAL WORKSHOP PRACTICE 4 TITLE
: PRACTICAL TASK WORKSHEET DRAWING (MACHINING)
DURATION
: 5 WEEKS
CLO 1
: Perform high precision machining processes for the surface or cylindrical grinding machine (P4, PLO5)
Instruction: 1. Produce a product of Task 1 and Task 2 in using conventional lathe, cylindrical grinding machine, milling machine and surface grinding machine. (85 marks) 2. Provide a report for producing product of Task 1 and Task 2 below. (80 marks)
TASK DIMENSION & DRAWING Task 1 - Cylindrical Grinder
Task 2 - Surface grinder
2
WORKSHOP SAFETY & REGULATIONS
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MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
WORKSHOP RULES AND REGULATIONS
1)
Always conduct yourself in a responsible manner in the laboratory.
2)
Follow all written and verbal instructions carefully. If you do not understand a direction or part of a procedure, ASK YOUR INSTRUCTOR BEFORE PROCEEDING WITH THE ACTIVITY.
3)
Never work alone in the laboratory. No student may work in the laboratory without the presence of the instructors.
4)
When first entering a laboratory, do not touch any equipment, chemicals, or other materials in the laboratory area until you are instructed to do so.
5)
Perform only those experiments authorized by your instructor. Carefully follow all instructions, both written and oral. Unauthorized experiments are not allowed.
6)
Do not eat food, drink beverages, or chew gum in the laboratory. Do not use laboratory glassware as containers for food or beverages.
7)
Be prepared for your work in the laboratory. Read all procedures thoroughly before entering the laboratory. Never fool around in the laboratory. Horseplay, practical jokes, and pranks are dangerous and prohibited.
8)
Always work in a well-ventilated area.
9)
Observe good housekeeping practices. Work areas should always be kept clean and tidy.
10)
Be alert and always proceed with caution in the laboratory. Notify the instructor immediately of any unsafe conditions you observe.
11)
Labels and equipment instructions must be read carefully before use. Set up and use the equipment as directed by your instructor.
12)
Experiments must always be personally monitored. Do not wander around the room, distract other students, startle other students or interfere with the laboratory experiments of others.
13)
Know the locations and operating procedures of all safety equipment including: first aid kit(s), and fire extinguisher. Know where the fire alarm and the exits are located.
14)
Dress properly during a laboratory activity. Long hair, dangling jewellery, and loose or baggy clothing are a hazard in the laboratory. Long hair must be tied back, and dangling jewellery and baggy clothing must be secured. Shoes must completely cover the foot. No sandals allowed on lab days.
15)
Report any accident (spill, breakage, etc.) or injury (cut, burn, etc.) to the lecturer or instructor immediately, no matter how trivial it seems. Do not panic.
3
PRACTICAL TASK WORKSHEET
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MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
1.0
Task Outcome
By the end of this task, student should be able to: 1.
Understand how to sketch object in 2D and the stages in the process.
2.
Use surface grinding machine and cylindrical grinding machine to complete the task given.
2.0
3.0
Apparatus and Equipment
1.
Conventional lathe machine
2.
Conventional milling machine
3.
Cylindrical grinder machine
4.
Surface grinder machine
5.
Vernier calliper
Theory
Introduction
Metal fabrication has begun centuries ago, starts with metal melting process to produce swords and armour. Metal melting process nowadays is known as casting process. However, fabricating a complicated shaped products with good surface finish is not always feasible and economical using a casting process. In order to get the desired final shape, various secondary operations can be performed on the casted products. The secondary operations are include joining such as welding, material removal or machining, heat treatment or property modification, colouring and coating. Many of such processes exist to offer the need of processing variety of materials in various ways and to finish the surfaces at different levels. Material removal processes basically removes material from workpiece surface to provide intended dimension and tolerance. Illustration of material removal process d=in machining is shown in Figure 1.
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MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
Figure 1.Material removal process in machining. (Kalpakjian S. & Schmid S.R, 2003, p684)
Metal cutting or known as machining is one of the secondary manufacturing processes. In machining, layer by layer material is gradually removed in the form of chips from a preformed workpiece to obtain a desired shape, size, and finish. To fulfill this need, various machining processes as in Figure 3 are used, which are turning, threading, tapering, chamfering, spinning, tapping, necking, filleting, facing, grooving, parting, knurling, drilling, milling, shaping, planning, slotting, boring, hobbing, and broaching. Such processes can provide higher material removal rate (MRR) and thus are suitable, productive and economic for bulk removal of work material. In a removing a material by shear, a cutter or a hard and sharp cutting tool is used. The cutter should have a defined specification and compatible with the material to be removed so that the material removal process is uninterrupted and smooth. Material removal layer by layer with cutting tool is illustrated in Figure 2. Most of the conventional processes can machine a large variety of materials. However certain materials do not have a good machinability and therefore, other material removal processes such as non-traditional machining (NTM) or abrasive cutting are recommended.
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MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
Figure 2.Cross section view of machining process (Groover P.Mikell, 2010, p. 484)
Grinding is one type of abrasive cutting process, that can fulfil various limitations of conventional machining. A grinding wheel is utilized and performed as of cutting tool. The wheel is basically made of small size and harder abrasive particles, like alumina, silica, diamond, etc., which are bonded in a suitable medium. During grinding process, material is removed in the form of chips with micro-sized chips. This process is not suitable for bulk removal of materials. Instead, it is preferred for finishing the surface in micron level (0.5 – 2.0µm). It can also efficiently ground hard and tough materials.
Figure 3.Classification of material removal processes. (Groover P.Mikell, 2010, p. 484)
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MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
Grinding operation can be classified into two different categories: 1) On the basis of quality of grinding; a) Rough grinding or non-precision grinding. b) Precision grinding.
2) On the basis of surface to be ground; a) External grinding b) Internal grinding c) Surface grinding d) Form grinding.
Process of Grinding
Grinding is the most common type of material cutting and surface generation process. As in Figure 4, grinding is an abrasive machining process which uses grinding wheel as a cutting tool. Mostly grinding process is used to shape and to provide better finishing parts of metals. Grinding process uses one abrasive tool to make controlled contact with workpiece surface.
Figure 4.Elements of the grinding process. (Rubio E. & Jauregui J.C., 2012. p.29)
In grinding process, the removing metal is performed by the application of abrasives material that is rubs against the workpiece and removes tiny pieces from the workpiece as shown in Figure 5. The abrasive material is typically in a form of a wheel or belt and abrades material in a way similar to sanding.
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MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
Figure 5. abrasive particles in a grinding wheel remove material from a workpiece, 2007, Retrieved from https://en.wikipedia.org/wiki/Grinding_(abrasive_cutting)/
Size of abrasive materials works a very important role in grinding process. Larger size grains will remove material faster from workpiece surface but did not provide the better surface finish. Whereas smaller grain size will remove material slowly from workpiece surface with better surface finish. These grains of abrasive material are termed as grits. Grits will have sharp edges or sharp points with enough hardness as compared to workpiece surface. Grits also have higher and wear resistance compared to workpiece surface. These grits will act as cutting tool in process of grinding to remove small particles from workpiece surface. According to society of manufacturing engineers, surface finishing and precision obtained from a grinding process will be approximate ten times better as compared to machining process performed by milling or turning. Performance of grinding wheel will be dependent on grain size, pore structure and bond type. Service life of grinding wheel will also depend on the application of coolant. Application of coolant in grinding process will reduce the power requirement of grinding machine as well as will provide the better quality of grinding also.
Advantage of grinding process
On its surface, grinding process seems simple but there are many variations, approaches, and considerations for this type of machining; each of which is particularly effective for certain applications with certain materials. Although the grinding process as much a cutting action as drilling, milling, and lathe turning, there are some reasons for grinding process to be chose as the removal process of material; i.
Can machine too hard material economically
ii.
grinding can produce flatness tolerances of less than +/-0.0025 mm.
iii.
machining removes excessive material. 8
MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
iv.
working principle and operation is simple
v.
does not require additional skills
vi.
surface finishing will be approximate 10 times better as compared to milling and turning.
vii.
Good dimensional accuracy
viii.
performed on hardened and unhardened part
ix.
can produce very accurate sizes
x.
equally accurate geometry like flatness or circle
xi.
extremely good surface finish
xii.
machining hardness high-speed steel, which cannot be done by other machining processes
Grinding process usually used for several reasons, for example: i.
to improve surface finish
ii.
to abrade hard materials
iii.
tighten the tolerance on flat and cylindrical surfaces
iv.
to finish off rough edges of tapered, straight, and formed holes
v.
deburr metal parts.
vi.
smooth the welds
vii.
create sharp edges.
viii.
create unique finished (jitterbug finish on a metal part).
ix.
sharpen the machine cutting tool
Disadvantages of grinding process
i.
Work surface gets over heated.
ii.
Wheel wear results duplicate parts do not have the same dimensions.
iii.
Grinding is not suitable for heavy metal removing.
iv.
For some complicated parts grinding needs attention.
v.
Achieving true parallelism requires skill.
vi.
Achieving concentricity needs attention.
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MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
Factor affecting the quality of ground workpiece surfaces
Various factors that influence the quality of workpiece surfaces prepared by process of grinding, such as: a) Type of grinding wheel: Grinding wheel with smaller grain size will provide the better surface finish, while material removal rate will be low. b) Feed rate: Slower feed rate will provide the precise surface finishing c) Material of workpiece: Material with much hardness will yield the precise surface finishing d) Grinding wheel condition: Damaged grinding wheel will never provide the quality surface finishing. e) Quality of lubricant: Quality coolant in grinding process will reduce the power requirement of grinding machine as well as will provide the better quality of grinding also.
On a microscopic scale, the chip formation in grinding is the same as that found in other machining processes. However, the abrasive action of grinding process generates excessive heat on the cutting surface area. The use of fluids in a grinding process is often necessary to cool and lubricate the wheel and workpiece as well as remove the chips produced in the grinding process.
Grinding Machine Operation
Grinding, or abrasive machining, once performed on conventional milling machines, lathes and shapers. The development in machining industry resulting the various designation of grinding machines. Grinding machines have advanced in design, construction, rigidity and the application far more in the last decade than any other standard machine tool in manufacturing industry. Numerous types of grinding operations are varied according to the shape of wheel and kinematic motions of the workpiece and wheelhead. More complex grinding machines are used to generate other shapes. Grinding machines fall into five categories: 1) surface grinders 2) cylindrical grinders 3) centerless grinders 4) internal grinders
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MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
Among of all the grinding machine categories, there are two of the most common ones are surface and cylindrical grinding. Therefore, a more detailed discussion and description in the next paragraph will relate to these two types of machines.
Cylindrical Grinding
The operation of cylindrical grinding is carried out on a cylindrical grinding machine as in Figure 6, either a plain-type grinding machine or the universal-type grinding machine. Cylindrical grinding process is used to shape the outer surface of a workpiece. This process is mostly used to grind the surface of cylindrical shape workpiece. The surfaces may be straight, tapered or contoured. Cylindrical grinding operations resemble the lathe-turning operations. These machines replace the lathe in material removal operation when the workpiece is hardened or when extreme accuracy and superior finish are required.
Figure 6.Illustration of cylindrical grinding machine and the parts, 2020, Retrieved from https://www.youtube.com/watch?v=lZH5kpJHBXg/
In cylindrical grinding operation, the workpiece is mounted between two centers. Following the Figure 6, one center is located on the headstock and the other center is on the tailstock. Both are rotated and revolved once the machine is turn on. The workpiece centers can transverse at various feeds so that the entire length of the workpiece passes to the wheel or in front of the wheel. During the grinding, the workpiece is fed longitudinally against the rotating grinding wheel. As the workpiece revolves, the grinding wheel which rotates faster in the opposite direction, is brought into contact with the workpiece. Cylindrical grinders have one wheelhead attached with spindle and 11
MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
motor. The grinding wheel is attached on the wheelhead; mounted on spindle. To perform the grind operation, this wheelhead will move to the object or from the object with the help of cross slide. A grinding wheel revolves at higher speed than the workpiece. The depth of cut for cylindrical grinding operation is small, for about 0.015 mm. When the entire workpiece has passed in front of the wheel, the wheel advances forward by another 0.015mm at the end of the transverse. The cycle of grinding is repeat until the desired diameter of the workpiece is reached. The result is a long cylinder of the perfectly circular profile with 443a very fine surface finish. Following Figure 7 shows the position of workpiece between centers and how the grinding wheel and cylindrical workpiece rotates during the cylindrical grinding operation. Figure 8 shows the actual setup of workpiece material on a cylindrical grinding machine with grinding wheel located near to workpiece to be ground.
Figure 7.Illustration of workpiece and grinding wheel position on cylindrical grinder machine, 2015, Retrieved from https://cadcamengineering.net/types-of-grinding-machines/
Figure 8.Grinding wheel on wheelhead to cut the workpiece with small depth of cut, 2019, Retrieved from https://www.mech4study.com/2019/01/types-of-grinding-machine.html/
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MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
Surface Grinding
Surface grinding process is generally the most common grinding techniques. The term surface grinding assign that any process which accurately processes or grinds a surface. Surface grinding methods are included horizontal spindle, vertical spindle, vertical spindle rotary grinding, vertical spindle single disk and vertical head grinding. Parts or workpieces may require a grinding process if there is a need to produce a flat surface with accurate thickness tolerance. Surface grinding also able to provide a part with specified and very smooth surface roughness. Surface grinding can be used for cutting tool sharpening. Surface grinding is used primarily for grinding and to obtain a desired flat surface finish or smoothness, precise angularity, perpendicularity and flatness tolerances. Surface grinding machines and processes where first developed to manufacture and removed material from very hard metals. A surface grinding machine normally consists of a magnetic chuck, which resembles a table, the grinding wheel that is attached to a rotating spindle, and a few handwheels for manually operated. A straight wheel is mounted on the horizontal spindle of the grinder. Transverse grinding occurs as the table reciprocates longitudinally and feeds laterally after each stroke. Surface grinding machine and all parts includes is illustrates in a diagram of Figure 9. The grinding wheel used is depends on the component being ground. Different grinding wheel compound for different type of material to be ground.
Figure 9. Parts of surface grinding machine, 2020, Retrieved from https://www.youtube.com/watch?v=mGR7oszv9SE/
On the surface grinding machine, the workpiece is placed on a magnetic chuck attached to a worktable of the grinder. The chuck is activated either by a switch or lever. When the chuck is activated, the part will then hold firmly to the magnetic chuck. Non-magnetic workpieces are held by vices or fixtures. 13
MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
The workpiece mounted on either a reciprocating or a rotary table is brought into contact with the grinding wheel. The workpiece will be feed in horizontal direction, below the grinding wheel, with the help of fed table. The abrasive grinding wheel rotates on a spindle and runs generally above the workpiece. This produces the desired surface finish along with the ability to grind to extremely high tolerances, with typically + /-0 .0001” or + / – 0 .002 mm. Once the grinding wheel is touching the workpiece surface, the worktable is set to move side to side and front to back until the entire surface of the part is ground. The movement of worktable is repeat with the grinding wheel brought close to touch the workpiece surface until the desired dimension is accomplished. The illustration of workpiece attached on the worktable and how the grinding wheel is positioned above the workpiece is shown in Figure 10 below. Figure 11 shows the actual setup of workpiece material on a surface grinding machine with grinding wheel located above to workpiece to be ground. There are sparks generate just after the grinding wheel rotated in high speed and touched surface of workpiece.
Figure 10.Position of workpiece on the worktable and grinding wheel is above the workpiece, 2015, Retrieved from https://cadcamengineering.net/types-of-grinding-machines/
Figure 11.Surface grinding operation produce sparks on the surface of workpiece, 2018, Retrieved from https://www.mech4study.com/2018/12/grinding-machining-process-complete-notes.html/
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MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
5.0
Procedures to complete the task *Please use the following work procedure together along with the machines’ safety and standard operation procedures.*
TASK 1
i)
Do the facing and parallel turning to produce a cylinder with 50mm length and 21mm diameter.
ii)
Mark a line of 25mm length on the workpiece.
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MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
iii) Continue the turning work at 25mm section B to produce the 17mm of diameter.
Continue turning
iv) Mark a line of 20mm length on workpiece. v)
Continue the turning work at 20mm section C to produce the 15mm of diameter.
Continue turning
vi) Do the centre drilling at the 50mm section and then the workpiece is ready for cylindrical grinding process. vii) Place the workpiece on the workhead and tailstock of cylindrical grinder machine. Procedure to set up workpiece on a cylindrical grinder are similar to procedure used to set up workpiece on lathe machine. For a center-type grinding process, one end of workpiece must be hold by chuck on the workhead while the other end must be placed on tailstock and supported at the same center hole drilled. Use center rests or steadyrest to support a long workpiece or overhanging ends of a workpiece. Position of all parts of cylindrical grinding machine are as shown in the Figure 12. viii) The procedures of set up a workpiece for center-type grinding process are as follows: a) Make sure the centers in the workhead and tailstock and the center holes on the workpiece are in good condition. b) Clamp a driving dog onto the workpiece.
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MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
c) Position the workhead and tailstock; and set the traverse stop dogs to guide the table to traverse longitudinally on the workpiece in the proper distance, during the grinding process. d) Make sure the workhead swivel, the taper table attachment and the wheelhead swivel are set properly.
Figure 13 illustrates the position and rotation direction of workpiece and grinding wheel after the work setup.
Figure 12.Sketch diagram of cylindrical grinding machine includes all parts. (Retrieved from https://www.mechtalk.info/2020/05/grinding-machine.html/)
Figure 13.Position of workpiece and grinding wheel for center-type cylindrical grinding, 2018,Retrieved from https://www.open.edu/openlearn/science-maths-technology/engineeringtechnology/manupedia/centreless-grinding/
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MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
TASK 2
*Please use the following work procedure along with the machines’ safety and standard operation procedures.*
Milling process i)
Measure the initial thickness of workpiece and thickness to be removed from workpiece.
ii)
Clamp the workpiece on the vertical milling machine. Position of all parts of milling machine are as shown in the Figure 14.
iii) Adjust the position of milling cutter facing the upside surface of workpiece. iv) Set the depth of cut (z-axis) position for milling cutter following the thickness to be removed from workpiece. v)
Do the face milling process on the workpiece in a way of layer by layer of side material removal. Figure 15 illustrates the schematic diagram of how milling cutter cuts and removes the layer of workpiece material during milling operation.
vi) Repeat procedure (vi) to produce a workpiece with the dimension of 45 mm x 45 mm x 14.5 mm.
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MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
Figure 14. Parts of milling machine, 2015, Retrieved from https://www.mechanicalbooster.com/2016/12/what-is-milling-machine-operation-parts-types.html/
Figure 15.Schematic of milling cutter remove the materials of workpiece. (Dahnel A. N, 2015, p.3)
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MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
Surface grinding process i.
Identify the thickest dimensions on the workpiece.
ii.
Place the workpiece on a worktable and switch on the magnetic chuck. The position of workpiece and grinding wheel is illustrates in Figure 16.
Figure 16.Illustration of workpiece position on worktable and the grinding wheel is place above the workpiece, 2012, Retrieved from https://engineerharry.wordpress.com/2012/04/21/grinding-machines-and-equipment/
iii.
Switch on the grinding wheel. Be careful of spark ignition. Make sure operator of this machine wearing a safety glass.
iv.
Lift the worktable slowly until the grinding wheel hit the thickest spot on the workpiece. When the workpiece produces a spark, it signs that grinding wheel hit the thickest spot on workpiece.
Figure 17.Parts of surface grinding machine shows worktable, wheel head and grinding wheel position on machine.(Girsang I.P. & Dhupia J.S.,2015, p.842)
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MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
v.
Move the magnetic chuck forward or behind the grinding wheel if necessary; to avoid continuous sparks ignition that might heat up the workpiece.
vi.
Set up the coordinate z-axis as 0.000 at DRO surface grinding machine.
vii.
Move the worktable of x-axis and y-axis to grind all surfaces of the workpiece.
viii.
Pull the worktable forward.
ix.
Move the table in z-axis direction for about 0.020mm maximum.
x.
Repeat step (vii) until the workpiece gain thickness of 14.00mm.
Figure 17 can be used as a reference to the position of all parts of surface grinding machine, and guide to the surface grinding machine setup before the grinding operation take place.
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PRACTICAL RUBRIC
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MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
PRACTICAL DIMENSION & EVALUATION RUBRIC
TASK 1
Task 1 - Dimension Checklist Scheme
5
4
3
2
1
Score
Mark
A
Length (45mm)
±0.2
±0.4
±0.6
±0.8
±1.0
x1
/5
B
Width (45mm)
±0.2
±0.4
±0.6
±0.8
±1.0
x1
/5
C
height (14.5-15 mm)
±0.2
±0.4
±0.6
±0.8
±1.0
x3
/15
Task 1- Evaluation Rubric Item
10
8
6
Surface grinding
uniform grinding marks
non-uniform grinding marks
grinding marks
Total
/35
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PRACTICAL DIMENSION & EVALUATION RUBRIC
TASK 2
Task 2- Dimension Checklist Item
5
4
3
2
1
Score
Mark
Length A
50mm
±0.2
±0.4
±0.6
±0.8
±1.0
x1
/5
Diameter.A
20mm
±0.2
±0.4
±0.6
±0.8
±1.0
x3
/15
Length B
25mm
±0.2
±0.4
±0.6
±0.8
±1.0
x1
/5
Diameter.B
17mm
±0.2
±0.4
±0.6
±0.8
±1.0
x1
/5
Length C
20mm
±0.2
±0.4
±0.6
±0.8
±1.0
x1
/5
Diameter.C
15mm
±0.2
±0.4
±0.6
±0.8
±1.0
x1
/5
Task 2- Evaluation Rubric Item
10
8
6
Cylindrical grinding section A
uniform grinding marks
non-uniform grinding marks
grinding marks Total
/50
23
REPORT RUBRIC
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MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
REPORT RUBRIC
TASK 1
Unsatisfactory
Fair
Good
Very good
1
2
3
4
1
Incomplete / out of the topics
Satisfactory information about the topics
Good information about the topics
Excellent and detail information about the topics
1
Incomplete / out of the topics
Satisfactory information about safety
Good information about safety
Excellent and detail information about safety
Incomplete / out of the topics
Satisfactory information about procedures taken without diagram
Good information about procedures taken with diagram but loss some point
Excellent and detail information about procedures taken with diagram
1
Incomplete / out of the topics
Satisfactory information about procedures taken without diagram
Good information about procedures taken with diagram but loss some point
Excellent and detail information about procedures taken with diagram
2
Out of topic and not related with course learning outcomes
Satisfactory discussion related to theory and course learning outcomes
Good explanation and discussion related to theory and course learning outcomes
Excellent explanation and discussion related to theory and course learning outcomes
3
Out of topic and not related with course learning outcomes
Satisfactory discussion related to theory and course learning outcomes
Good explanation and discussion related to theory and course learning outcomes
Excellent explanation and discussion related to theory and course learning outcomes
1
Retrieve relevant information from only one sources
Retrieve relevant information from two sources
Retrieve relevant information from three sources
Retrieve relevant information from four and above sources
Skill/ Aspect
Marks Weight
Introduction
Safety precautions
SOP for Turning on Lathe
SOP for Cylindrical Grinding Machine
Facing and turning process
Cylindrical grinding process
Reference
1
MARKS
TOTAL
/ 40
TOTAL
/100
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MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
REPORT RUBRIC
TASK 2
Unsatisfactory
Fair
Good
Very good
1
2
3
4
1
Incomplete / out of the topics
Satisfactory information about the topics
Good information about the topics
Excellent and detail information about the topics
1
Incomplete / out of the topics
Satisfactory information about safety
Good information about safety
Excellent and detail information about safety
Incomplete / out of the topics
Satisfactory information about procedures taken without diagram
Good information about procedures taken with diagram but loss some point
Excellent and detail information about procedures taken with diagram
1
Incomplete / out of the topics
Satisfactory information about procedures taken without diagram
2
Out of topic and not related with course learning outcomes
Satisfactory discussion related to theory and course learning outcomes
3
Out of topic and not related with course learning outcomes
Satisfactory discussion related to theory and course learning outcomes
Good information about procedures taken with diagram but loss some point Good explanation and discussion related to theory and course learning outcomes Good explanation and discussion related to theory and course learning outcomes
Excellent and detail information about procedures taken with diagram Excellent explanation and discussion related to theory and course learning outcomes Excellent explanation and discussion related to theory and course learning outcomes
1
Retrieve relevant information from only one sources
Retrieve relevant information from two sources
Retrieve relevant information from three sources
Retrieve relevant information from four and above sources
Skill/ Aspect
Marks Weight
Introduction
Safety precautions
SOP For Milling Machine
SOP For Surface Grinding Machine Side milling and surface milling process
Surface grinding process
Reference
1
MARKS
TOTAL
/ 40
TOTAL
/100
25
TUTORIAL QUESTIONS
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MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
TUTORIAL QUESTIONS
TOPIC : GRINDING MACHINE
1. Who invented grinding machine? 2. What are grinding machines used for? 3. What is a universal grinding machine? 4. What are the process of grinding? 5. Is grinding a machining process? 6. What are the types of grinding? 7. How grinding machines are classified? 8. Which of the following is not a benefit of applying coolants in a grinding operation? a) The area between the grinding wheel and the work piece is lubricated b) Bits of the grinding wheel and metal (swarf) are flushed away from the work c) Metal is washed off the surface of the grinding wheel providing a continuous cleaning action d) The temperature of the grinding wheel and work piece is reduced
TOPIC : CYLINDIRCAL GRINDING
1. What Is Cylindrical Grinding? 2. What is the use of cylindrical grinders? 3. How does a cylindrical grinder work? 4. What is the difference between plain and universal cylindrical grinder? 5. What is a primary difference between surface grinding and cylindrical grinding? 6.
One method of obtaining a fine finish when using a surface grinder is to: a) Take a light cut and apply coolant b) Take a depth of cut that exceeds .003” c) Increase the feed rate by .5 d) Use an soft wheel with an open structure
26
MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
7. In the illustration, the longitudinal hand wheel is designated by the letter: a) A b) B c) C d) D e) E
8. In the illustration, the down feed hand wheel is designated by the letter: a) A b) B c) C d) D e) E
TOPIC : SURFACE GRINDING
1. What Is Surface Grinding? 2. How does a surface grinder work? 3. What is the final product of surface grinding? 4. What types of work can be ground by a surface grinder? 5. What are the two types of magnetic chucks? 6. What is the use of magnetic chuck in surface grinding? 7. How are the non-ferrous metals held in magnetic chuck?
27
MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
REFERENCES
1. Kalpakjian S. & Schmid S. R. (2003) Manufacturing Engineering and Technology (6th ed.) In Si Units [Photograph]. Prentice Hall 2. Groover P. Mikell. (2010). Fundamental of Modern Manufacturing: Material, Processes and Systems (4th ed.). [Photograph]. John Wiley & sons. Inc 3. Groover P. Mikell. (2010). Fundamental of Modern Manufacturing: Material, Processes and Systems (4th ed.). [Photograph]. John Wiley & sons. Inc 4. Rubio E. & Jauregui J.C. (2012). A Wavelet Approach to Estimate the Quality of Ground Parts [Photograph]. Journal of Applied Research and Technology 10(1):28-37. DOI 10.22201 / icat.16656423.2012.10.1.418 5. Jahobr.
(2007)
Grinding
(abrasive
cutting)
[Photograph].
Retrieved
from
https://en.wikipedia.org/wiki/Grinding_(abrasive_cutting) 6. AK All Education. (2020) Cylindrical Grinding Machine [Photograph]. Retrieved from https://www.youtube.com/watch?v=lZH5kpJHBXg 7. Cad cam Engineering WorldWide. (2015) Types of Grinding Machines [Photograph]. Retrieved from https://cadcamengineering.net/types-of-grinding-machines 8. mech4study
(2019).
Types
of
Grinding
Machine
[Photograph].
Retrieved
from
https://www.mech4study.com/2019/01/types-of-grinding-machine.html
9. AK All Education. (2020) Surface Grinding Machine [Photograph]. Retrieved from https://www.youtube.com/watch?v=mGR7oszv9SE 10. Cad cam Engineering Worldwide. (2015) Types of Grinding Machines [Photograph]. Retrieved from https://cadcamengineering.net/types-of-grinding-machines 11. Mech4study Admin. (2018) Grinding Machining Process: Complete Notes [Photograph]. Retrieved
from
https://www.mech4study.com/2018/12/grinding-machining-process-
complete-notes.html 12. K.Saha.
(2020).
Grinding
Machine
or
Grinder
[Photograph].
Retrieved
from
https://www.mechtalk.info/2020/05/grinding-machine.html/ 13. The Open University (2018). Centreless grinding
[Photograph]. Retrieved from
https://www.open.edu/openlearn/science-maths-technology/engineeringtechnology/manupedia/centreless-grinding/
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MECHANICAL WORKSHOP PRACTICE 4 (MACHINING) WORKBOOK
14. Pankaj Mishra. (2015). What is Milling Machine – Operation, Parts and Types [Photograph]. Retrieved
from
https://www.mechanicalbooster.com/2016/12/what-is-milling-machine-
operation-parts-types.html/ 15. Dahnel A. N. et. al (2015). Study Of Cutting Forces and Surface Roughness in Milling of Carbon Fibre Composite (Cfc) With Conventional And Pressurized Co2 Cutting Fluids. ASME 2015 International Mechanical Engineering Congress and Exposition. DOI: 10.1115/IMECE201550419 16. Baik Chong Hyun (2012). Grinding Machines and Equipment [Photograph]. Retrieved from https://engineerharry.wordpress.com/2012/04/21/grinding-machines-and-equipment/ 17. Girsang I.P. & Dhupia J.S. (2015). Machine Tools for Machining. Handbook of Manufacturing Engineering and Technology. DOI:10.1007/978-1-4471-4670-4_4 (pp.811-865)
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