00193407-02 HWWS SIPLACE Machine Accuracy EN.pdf - 第13页

© Siemens AG . . Änderungen vorbehalten SIPLACE Placement Systems Quality Evaluation For an evaluation of qual ity, a comparison with the spec ifications is necessary. The specifications determine t he upper and l owe r …

SIPLACE

Placement Systems

Machine capability indices Cmk

Machine capability, e.g. min. C

= 1,33 (4 Sigma specification))

Cmk: position of the mean value of the series of measurements as well as the dispersion

¾ the machine capability is just a snap-shot and is performed with proper

measurement tools.

Cmk = Min (Cmk 1, Cmk 2) meaning the lowest value is only used for the Cmk

The centering index k is a measure of the deviation of the mean process value from the target value

(center of tolerance).

If the machine parameters are perfectly centered, k = equal to zero, and Cmk = equal to Cm.

Machine Capability

3 x Sigma

USG - Offset

Cmk 1 =

3 x Sigma

OSG - Offset

Cmk 2 =

SIPLACE

Placement Systems

Quality Evaluation

For an evaluation of quality, a comparison with the specifications is necessary.

The specifications determine the upper and lower parameters, which during the process may not

be exceeded.

Each process has a determined set-point value which must be achieved. Each deviation from

this desired value includes additional risks .

centering and dispersion

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.. . ... .. .

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. ...

... ..

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. ...

... ..

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dispersion to

high

Cmk < 1.33

(4 sigma)

dispersion good,

centering not good

(offset high)

dispersion good,

centering good.

Cmk > 1.33

(4 sigma)

Cm value equal

the higher the Cm and Cmk, the better

Machine Capability

SIPLACE

Placement Systems

Cm >1.33, Cpk >1.33

Cm <1.33, Cmk < 1.33

Cmk <1.33

Cm >1.33

Cm <1.33, Cmk < 1.33

example: specification 50 um at 4 Sigma

Machine Capability