NTTF, Bangalore

PRINCIPLES OF LOCATION• IN INTERCHANGEABLE MANUFACTURING

PROCESS WHEN A WORKPIECE IS PLACED ON A MACHINE TABLE, SPINDLE, JIG OR FIXTURE IT MUST BE PROPERLY POSITIONED BEFORE IT IS CLAMPED

• IT IS THE DUTY OF THE LOCATION SYSTEM TO PROVIDE ALL NECESSARY CONSTRAINTS SO THAT THE WORKPIECE IS CORRECTLY LOCATED AND ALL POSSIBLE MOVEMENTS OF THE WORKPIECE ARE RESTRICTED.

NTTF, Bangalore

TWELVE DEGREES OF FREEDOM• A WORK PIECE IN SPACE IS FREE TO

MOVE IN ANY DIRECTION AND CAN HAVE TWELVE DEGREES OF FREEDOM

• EACH DIRECTION OF MOVEMENT IS CONSIDERED ONE DEGREE OF FREEDOM

• IT CAN MOVE IN EITHER OF OPPOSED DIRECTIONS ALONG THREE MUTUALLY PERPENDICULAR AXES AND MAY ROTATE IN EITHER OF TWO OPPOSED DIRECTIONS AROUND EACH AXES i.e. CLOCKWISE AND COUNTERCLOCKWISE

NTTF, Bangalore

THE DUTY OF THE LOCATION SYSTEM

THE LOCATION SYSTEM MUST, IN CONJUNCTION WITH THE CLAMPING SYSTEM COMPLETELY CONSTRAIN THE WORKPIECE OR ELIMINATE AS MANY OF THE 12 DEGREES OF FREEDOM AS IS NECESSARY FOR THE OPERATION TO BE COMPLETED WITH THE REQUIRED ACCURACY

NTTF, Bangalore

DEGREES OF FREEDOM IN SPACE

NTTF, Bangalore

THE CHOICE OF LOCATION SYSTEM

• THE REQUIREMENTS OF THE LOCATION SYSTEM DEPEND UPON THE OPERATION BEING PERFORMED AND UPON THE WORKPIECE BEFORE THE OPERATION.

NTTF, Bangalore

PRIMARY DATUM

• Primary datum: This establishes the orientation of the part (stablise the part ) to the datum reference frame.The part contacts the datum plane with at least three points of contact.The primary datum restricts FIVE degree of freedom ( four rotary and one linear)

NTTF, Bangalore

SECONDARY DATUM• Secondary datum: This locates the part

(restricts part movement) within the datum reference frame.Requires a minimum of two points of contact with the secondary datum.The Secondary datum restricts THREE additional degree of freedom ( Two rotary and One linear )

NTTF, Bangalore

TERTIARY DATUM

• Tertiary datum: This locates the part(restricts part movement) within the datum reference frame.Requires a minimum of one points of contact with the secondary datum.The tertiary datum restricts the ONE degree of freedom ( Linear )

NTTF, Bangalore

Primary, Secondary and Tertiary Datums

NTTF, Bangalore

THE 3-2-1 RULE

• The 3-2-1 rule defines the minimum number of points of contact required.

• The 3-2-1 rule only applies on a part with all planar datums.

NTTF, Bangalore

DATUM REFRENCE FRAME

NTTF, Bangalore

CONSTRAINING REMAINING DEGREES OF FREEDOM

• THE 10TH DEGREE OF FREEDOM IS ARRESTED BY FIRST CLAMP AGAINST SECONDARY DATUM

• THE 11TH DEGREE OF FREEDOM IS ARRESTED BY SECOND CLAMP AGAINST TERTIARY DATUM

• THE 12TH DEGREE OF FREEDOM IS ARRESTED BY EITHER DOWNWARD CLAMP OR BY GRAVITY ( IF WORKPIECE IS HEAVY)