【正文】 . 5 3 1 1 8 . 5 4 1 1 8 . 5 59 th Su b g r o u p 1 0 th Su b g r o u p 1 1 th Su b g r o u p 1 2 th Su b g r o u p1 1 8 . 6 0 1 1 8 . 6 1 1 1 8 . 5 8 1 1 8 . 6 01 1 8 . 5 9 1 1 8 . 6 0 1 1 8 . 6 0 1 1 8 . 6 31 1 8 . 5 8 1 1 8 . 6 1 1 1 8 . 6 1 1 1 8 . 6 31 1 8 . 6 0 1 1 8 . 5 9 1 1 8 . 6 0 1 1 8 . 6 11 1 8 . 5 9 1 1 8 . 5 9 1 1 8 . 5 9 1 1 8 . 6 412 169。 NOKIA 2001 Process Capability What is it? ? Process Capability is a measure of the inherent capability of a manufacturing process to be able to consistently produce ponents that meet the required design specifications ? Process Capability is designated by Cp and Cpk ? Process Performance is a measure of the performance of a process to be able to consistently produce ponents that meet the required design specifications. Process Performance includes special causes of variation not present in Process Capability ? Process Performance is designated Pp and Ppk 13 169。 NOKIA 2001 Why Make Process Capability Studies LSL (lower specification limit) 10,7 USL (upper specification limit) 10,9 Nominal 10,8?0,1 This part is within spec. The tool would be approved if only this part was measured These parts are out of spec and could be approved if only one good part was measured A process capability study would reveal that the tool should not be accepted When a dimension needs to be kept properly within spec, we must study the process capability …. but still this is no guarantee for the actual performance of the process as it is only an initial capability study 14 169。 NOKIA 2001 E1 E2 E3 E4 E5 The Nokia Process Verification Process Black diamonds to be fixed by E3 (often a change of a white diamond) Proposal for black diamonds to be discussed with Supplier. Max: 105,85 Ongoing Process Control (SPC) Tolerances applied to drawing 1 part/cavity measured for measurement report White diamonds(s) to be agreed White diamonds(s) to be discussed with supplier 10 parts/cavity measured for measurement report Capability study: Requirement: Cp and Cpk by E3. Quantities to be agreed with supplier. Minimum 5 parts pr 1/2 hour in 10 hours measured for each cavity = 100 parts. Can vary depending on tool capacity, . stamped parts (see DMY00019EN) 15 169。 NOKIA 2001 Section 2. Population, Sample and Normal Distribution 16 169。 NOKIA 2001 The Bell Shaped (Normal) Distribution ? Symmetrical shape with a peak in the middle of the range of the data. ? Indicates that the input variables (X39。s) to the process are randomly influenced. 17 169。 NOKIA 2001 “ Population Parameters” ? = Population mean ? = Population standard deviation Population versus Sample Population ? An entire group of objects that have been made or will be made containing a characteristic of interest Sample ? The group of objects actually measured in a statistical study ? A sample is usually a subset of the population of interest “ Sample Statistics” x = Sample mean s = Sample standard deviation 18 169。 NOKIA 2001 The Normal Distribution 19 169。 NOKIA 2001 What Measurements Can Be Used to Describe a Process or System ? x x x xN N? ? ? ?1 2 . . .Example: x1 = 5 x2 = 7 x3 = 4 x4 = 2 x5 = 6 62475 ???????x? mean (average) or describes the location of the distribution x? 181。 (m252。), a measure of central tendency, is the mean or average of all values in the population. When only a sample of the population is being described, mean is more properly denoted as (xbar) : x20 169。 NOKIA 2001 ),...,m i n (),...,m a x ( 2121 NN xxxxxxR ??Example: x1 = 5 x2 = 7 x3 = 4 x4 = 2 x5 = 6 527)6,2,4,7,5m i n ()6,2,4,7,5m a x ( ?????R? The most simple measure of variability is the range. The range of a sample is defined by as the difference between the largest and the smallest observation from samples in a subgroup, . 5 consecutive parts from the manufacturing pro