Lesson 66 of Industrial Engineering ONLINE Course.
Lesson 67. Selection of Metal Removal Processes - Initial Steps - Process Planning and Process Industrial Engineering
1 Drawing
1.1Dimensioning Dimensioning from datum
1.2 Redundant dimensioning
1.3 Stackup of tolerances by arithmetic method
1.4 Geometric tolerances
1.5 Geometric tolerances interpretation
1.6 Surface roughness
1.6.1 Definition of surface finish methods
2.Production Drawing Tolerances
Process planners have to understand the functional requirements of the design and can suggest design changes that make production easy and economical.
2.1 Tolerancing in production
Any dimension and its surface finish are not achieved in one production operation. Therefore, each production operation are to be specified with a tolerance such that the sum of all the tolerance results in the tolerance specified for the component at the end of the final operation.
2.1.1 Process to meet geometric tolerances
Causes of geometric deviations
1. Fixturing: Multiple fixturing increases deviations.
2. Machine accuracy and rigidity
3. Tool accuracy
4. Tool deflection
5. Cutting temperature
6. Vibrations in machine tool and cutting tool
7. Material heterogeneities
8. Kinematics
Hence careful choice and combination of machine tools, cutting conditions, tooling and fixtures and production operation level of tolerance strategies are required to achieve the tolerances specified in component drawing.
2.1.2 Production tolerancing
2.2 Tolerances in forming operations
3 Short Review of Statistical Tolerancing
3.1 Process Capability
1 Drawing
Basics of Engineering Drawings - Reading Drawings
___________
https://www.youtube.com/channel/UC9eqr6EBMP9cOZHwSjGeAKA
_____________
1.1 Dimensioning from datum
For the dimensions of parts that would assemble, the dimensioning should originate at a datum. The datum is indicated in the drawing.
1.2 Redundant dimensioning
In a given direction, a surface should be indicated by one and only dimension.
_____________
_____________
_____________
_____________
1.3 Stackup of tolerances by arithmetic method
For examples in case of step turning with multiple steps, the interval tolerance of the result is equal to the sum of the tolerances of the components in length.
1.4 Geometric tolerances
The geometrical tolerances of form and positions are defined in the ISO standard for Tolerances for Form and Position (ISO Standard 111, 1983)
Terminology of Geometric Tolerances
Category Characteristics
Form Flatness
Orientation Perpendicularity
Location Position
Runout Circular Runout
Profile Profile of a line
1.5 Geometric tolerances interpretation
___________________
https://www.youtube.com/watch?v=oXqYOKF7Q7U
___________________
___________________
https://www.youtube.com/watch?v=NArW09DFhf8
___________________
___________________
https://www.youtube.com/watch?v=yEIX0gIa5Tk
Channel https://www.youtube.com/channel/UCFw3UXCq7iG3LBh4JyK5d0A
___________________
1.6 Surface roughness
1.6.1 Definition of surface finish methods
Surface Finish Parameters used in industry today.
1. Arithmetic Average Roughness
2. Geometric Average Roughness
3. Peak-to-Valley Roughness Height
4. Ten-Point Height
5. Bearing Length Ratio
6. Peak Count
Related Articles
Surface Finish - Industrial Engineering and Productivity Aspects
Surface Finish, Integrity and Flatness in Machining
2.Production Drawing Tolerances
Process planners have to understand the functional requirements of the design and can suggest design changes that make production easy and economical.
2.1 Tolerancing in production
Any dimension and its surface finish are not achieved in one production operation. Therefore, each production operation are to be specified with a tolerance such that the sum of all the tolerance results in the tolerance specified for the component at the end of the final operation.
2.1.1 Process to meet geometric tolerances
Causes of geometric deviations
1. Fixturing: Multiple fixturing increases deviations.
2. Machine accuracy and rigidity
3. Tool accuracy
4. Tool deflection
5. Cutting temperature
6. Vibrations in machine tool and cutting tool
7. Material heterogeneities
8. Kinematics
Hence careful choice and combination of machine tools, cutting conditions, tooling and fixtures and production operation level of tolerance strategies are required to achieve the tolerances specified in component drawing.
2.1.2 Production tolerancing - Feasibility
Halevi gave the example of set up with fixture repeatability of 0.1 mm and the machine accuracy of 0.02 mm. When the counterbore is made this machine and fixture, the length of the internal minor diameter will come 20 + or - 0.04. It is acceptable because the required dimension is 20 + or - 0.1 mm.
The total length of the work piece is 70 mm, minor bore is 20 mm and counter bore length is 30 mm. So the length of the uncut portion is 20 mm and with this present errors it will come out to be 20 + or - 0.14. Acceptable because required dimension is 20 + or - 0.15.
But if machine accuracy is 0.03 mm, the resulting dimension tolerance will be 20 + or - 0.16. Not acceptable. Hence it is important to know the error quantities and see whether the machine and accessories in combination can produce the part to the specification or not.
2.2 Tolerances in forming operations
Halevi has given the example of a die working on a sheet metal blank. He says errors or tolerances achieved are of three types.
1. Tool dependent dimensions.
2. non-tool-dependent and
3. non-tool dependent dimensions in the direction of the closing the tool (travel of the punch).
Machine accuracy is estimated by type three errors. Improvement of machine accuracy and jigs and fixtures will minimize type 2 errors. Tool accuracy has to be improved for type 1 errors.
3 Short Review of Statistical Tolerancing
3.1 Process Capability
4. Technical Drawings
1 Drawing
1.1Dimensioning Dimensioning from datum
1.2 Redundant dimensioning
1.3 Stackup of tolerances by arithmetic method
1.4 Geometric tolerances
1.5 Geometric tolerances interpretation
1.6 Surface roughness
1.6.1 Definition of surface finish methods
2.Production Drawing Tolerances
Process planners have to understand the functional requirements of the design and can suggest design changes that make production easy and economical.
2.1 Tolerancing in production
Any dimension and its surface finish are not achieved in one production operation. Therefore, each production operation are to be specified with a tolerance such that the sum of all the tolerance results in the tolerance specified for the component at the end of the final operation.
2.1.1 Process to meet geometric tolerances
Causes of geometric deviations
1. Fixturing: Multiple fixturing increases deviations.
2. Machine accuracy and rigidity
3. Tool accuracy
4. Tool deflection
5. Cutting temperature
6. Vibrations in machine tool and cutting tool
7. Material heterogeneities
8. Kinematics
Hence careful choice and combination of machine tools, cutting conditions, tooling and fixtures and production operation level of tolerance strategies are required to achieve the tolerances specified in component drawing.
2.1.2 Production tolerancing
2.2 Tolerances in forming operations
3 Short Review of Statistical Tolerancing
3.1 Process Capability
1 Drawing
Basics of Engineering Drawings - Reading Drawings
___________
https://www.youtube.com/channel/UC9eqr6EBMP9cOZHwSjGeAKA
_____________
1.1 Dimensioning from datum
For the dimensions of parts that would assemble, the dimensioning should originate at a datum. The datum is indicated in the drawing.
1.2 Redundant dimensioning
In a given direction, a surface should be indicated by one and only dimension.
_____________
_____________
_____________
_____________
1.3 Stackup of tolerances by arithmetic method
For examples in case of step turning with multiple steps, the interval tolerance of the result is equal to the sum of the tolerances of the components in length.
1.4 Geometric tolerances
The geometrical tolerances of form and positions are defined in the ISO standard for Tolerances for Form and Position (ISO Standard 111, 1983)
Terminology of Geometric Tolerances
Category Characteristics
Form Flatness
Orientation Perpendicularity
Location Position
Runout Circular Runout
Profile Profile of a line
1.5 Geometric tolerances interpretation
___________________
https://www.youtube.com/watch?v=oXqYOKF7Q7U
___________________
___________________
https://www.youtube.com/watch?v=NArW09DFhf8
___________________
___________________
https://www.youtube.com/watch?v=yEIX0gIa5Tk
Channel https://www.youtube.com/channel/UCFw3UXCq7iG3LBh4JyK5d0A
___________________
1.6 Surface roughness
1.6.1 Definition of surface finish methods
Surface Finish Parameters used in industry today.
1. Arithmetic Average Roughness
2. Geometric Average Roughness
3. Peak-to-Valley Roughness Height
4. Ten-Point Height
5. Bearing Length Ratio
6. Peak Count
Related Articles
Surface Finish - Industrial Engineering and Productivity Aspects
Surface Finish, Integrity and Flatness in Machining
2.Production Drawing Tolerances
Process planners have to understand the functional requirements of the design and can suggest design changes that make production easy and economical.
2.1 Tolerancing in production
Any dimension and its surface finish are not achieved in one production operation. Therefore, each production operation are to be specified with a tolerance such that the sum of all the tolerance results in the tolerance specified for the component at the end of the final operation.
2.1.1 Process to meet geometric tolerances
Causes of geometric deviations
1. Fixturing: Multiple fixturing increases deviations.
2. Machine accuracy and rigidity
3. Tool accuracy
4. Tool deflection
5. Cutting temperature
6. Vibrations in machine tool and cutting tool
7. Material heterogeneities
8. Kinematics
Hence careful choice and combination of machine tools, cutting conditions, tooling and fixtures and production operation level of tolerance strategies are required to achieve the tolerances specified in component drawing.
2.1.2 Production tolerancing - Feasibility
Halevi gave the example of set up with fixture repeatability of 0.1 mm and the machine accuracy of 0.02 mm. When the counterbore is made this machine and fixture, the length of the internal minor diameter will come 20 + or - 0.04. It is acceptable because the required dimension is 20 + or - 0.1 mm.
The total length of the work piece is 70 mm, minor bore is 20 mm and counter bore length is 30 mm. So the length of the uncut portion is 20 mm and with this present errors it will come out to be 20 + or - 0.14. Acceptable because required dimension is 20 + or - 0.15.
But if machine accuracy is 0.03 mm, the resulting dimension tolerance will be 20 + or - 0.16. Not acceptable. Hence it is important to know the error quantities and see whether the machine and accessories in combination can produce the part to the specification or not.
2.2 Tolerances in forming operations
Halevi has given the example of a die working on a sheet metal blank. He says errors or tolerances achieved are of three types.
1. Tool dependent dimensions.
2. non-tool-dependent and
3. non-tool dependent dimensions in the direction of the closing the tool (travel of the punch).
Machine accuracy is estimated by type three errors. Improvement of machine accuracy and jigs and fixtures will minimize type 2 errors. Tool accuracy has to be improved for type 1 errors.
3 Short Review of Statistical Tolerancing
3.1 Process Capability
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