8/11/2019 Makmal Metro

1/3

Manufacturing Processes Lab MEM564 / LS03/Ziyadi Rev. 01-2014

UNIVERSITI TEKNOLOGI MARA

FAKULTI KEJURUTERAAN MEKANIKAL

Program : Bachelor of Mechanical Engineering (Manufacturing)(Hons)(EM221/241)

Bachelor of Engineering (Hons) Mechanical (EM220)

Course : Manufacturing Processes Laboratory

Course Code : MEM564

Course Outcome: CO1,CO2,CO3,CO4

LAB SHEET NO: 3

1.0 TITLE: Screw Thread Measurement

2.0 INTRODUCTION

2.1 Screw Plug Gauge Parameters

2.1.1 Major Diameter

Referring to the illustration:

Micrometer reading over Standard Cylinder = R1

Micrometer reading over Screw Plug Gauge = R2

Diameter of Standard Cylinder = D1

Major Diameter of Screw Plug Gauge, Dmajor = D1+ ( R2- R1) Eq. 1

8/11/2019 Makmal Metro

2/3

Manufacturing Processes Lab MEM564 / LS03/Ziyadi Rev. 01-2014

2.1.2 Minor Diameter

Referring to the illustration:

Micrometer reading over Standard Cylinder and Core Prisms = R3

Micrometer reading over thread and Core Prisms = R4Diameter of Standard Cylinder = D1

Minor Diameter of Screw Plug Gauge, Dminor = D1+ (R4R3) Eq. 2

2.1.3 Effective Diameter

Referring to the illustration:

Micrometer reading over Standard Cylinder and wire cylinders = R5

Micrometer reading over screw thread and wire cylinders = R6

Diameter of Standard Cylinder = D1

Diameter under the wire cylinders D3= D1+ ( R6R5 ) Eq. 3

Hence, the Effective Diameter Deff = D3+ Pwhere P is the difference between the Effective Diameter and the

diameter under the wires as shown below.

The P value is a constant depending on the diameter of the wires (d), the pitch (p) and the type of screw thread,it is found as follows:

Metric threads (600) P = 0.86602p - d

Whitworth threads (550) P = 0.96049p -1.16568d

British Association threads (47 1/20) P = 1.13634p -1.43295d

8/11/2019 Makmal Metro

3/3

Manufacturing Processes Lab MEM564 / LS03/Ziyadi Rev. 01-2014

3.0 OBJECTIVE

To measure the Screw Plug Gauge parameters using Floating Carriage Diameter Measuring Machine.

4.0 APPARATUS

A Floating Carriage Diameter Measuring Machine

A set of Core Prisms (Steel Prisms)

A set of calibrated screw thread measuring wires (Wire Cylinders)

A set of Metric Cylindrical Standards

A Screw Plug Gauge

5.0 METHOD OF APPROACH

A briefing session will be conducted prior to students carrying out the measurement on the specimen.Please take note of the procedures for setting up the specimen on the Floating Carriage Diameter

Measuring Machine. Movements can be made through micrometer adjustment. Parameters to bemeasured on the specimen are:

Major Diameter

Minor Diameter

Effective Diameter

Corrections to be incorporated in the above measurements are:

Rake Correction due to tilt of wires on account of rake, c. Compression Correction, e.

Note

The value of the Rake Correction and the Compression Correction for screw plug gauge can be found fromreference book (e.g. Practical Engineering Metrology, by K.J. Hume,Chapter 7)

6.0 LAB REPORT PREPARATION:

The report should include the following items:

Tabulation of reading parameters (min 3 readings) and overall results.

Calculation of the percentage of error for each of those parameters.

Evaluation of by comparing with the theoretical value by (refer to Metric Standard table forscrew thread (ISO 6H))

*Student should use the standard cover page.

*The report content should base on 10 items highlighted in standard report descriptions.