Packaging disfigurement and sampling

ITEM

DEFECT DESCRIPTION

Glass Container

weight or OFC out of spec.

broken ware

split finish

chipped finish

check

bent neck

white sports on inner surface

wrong decoration

dirty

Plastic Container

weight or OFC. out of spec

uneven rim at mouth area

flow traces in mouth dirty)

excess flash

poor printing

chocked neck

over ride

foreign material in plastic

dust,soot,dirt on container

out-of-shape ware

light (thin) ware

Cap / Cover

dimension out of spec.

dose not fit and seal container

missing or loosing liner

excess glue

excess flash

broken

scratched or scuffed

foreign spots in material

loose metal ring

Tube

functional dimensions out of spec.

clogged orifice

stuck together damage appearance

excess flash

warpped

coating peel of

over ride

Barrel

dimensions out of spec.

missing component part.

loose, tight or incorrect assembly of component parts

color outside limits

over ride

dirty

Compact

loose or tight closure, or incorrect assembly of component parts

top and bottom halves of compacts not meeting properly

broken,bent,cracked,or distorted hinges or catches

MIL-STD-105 抽样方案

MIL-STD-105 Sampling Scheme

Sampling plans are usually selected for given quality levels such as AQL, a, LQL, and b. The selected plan will have to be repeatedly used for each of the submitted lots if the quality levels remain unchanged. If the quality history is good, as evidenced by consecutive lot acceptances, then it may be desirable to reduce the amount of inspection. If the quality history is found to be bad (more lot rejections), then it is essential to tighten the inspection either by increasing the sample size or reducing the acceptance numbers. A specific plan selected for given quality levels has no mechanism to adjust according to the observed quality history. In such situations, the use of more than one plan is desirable with an associated rule for using each plan.

An acceptance sampling scheme is a specific set of procedures which usually consists of acceptance sampling plans in which lot sizes, sample sizes, and acceptance criteria, or the amount of 100% inspection, are related. Such schemes typically contain rules for switching from one plan to another. MIL-STD-105 E (1989) is an example for a sampling scheme.

A normal inspection plan is the plan used when the process is considered to be operating at, or slightly better than, the AQL.

A tightened inspection plan is a plan for using stricter acceptance criteria than those used in normal inspection.

A reduced inspection plan is a plan which permits smaller sample sizes than those used in normal inspection.

The main objective of using tightened inspection is to exert pressure on the producer when the quality is poorer than the AQL by introducing a higher rate of rejection. When the level of the submitted quality is sufficiently good, reduced inspection offers sampling economy. For example, consider the following single sampling plans having three different inspection intensities.
 

Normal: n = 125, Ac = 1, Re = 2
Tightened: n = 200, Ac = 1, Re = 2
Reduced: n = 50, Ac = 0, Re = 1

These plans can be operated in a sampling scheme provided that there are rules for switching between them.

MIL-STD-105 E (1989) is an AQL indexed standard. Here, the AQL is defined as the percent defective (or the maximum number of defects per 100 units) that for the purposes of sampling inspection, is considered satisfactory as a process average. MIL-STD-105 E contains three inspection intensities namely, normal, reduced and tightened plans. Single, double and multiple sampling plans are available, and plans of same inspection level are matched. This means that one may use single, double or multiple sampling plans depending on the sampling economy or reduction in complexity required, giving the same level of protection to the producer or consumer. In order to implement the switching rules, a table of limit numbers for reduced inspection is also available. The scheme also contains supplementary tables and graphs of limiting quality values, OC curves, ASN curves for double and multiple sampling plans which are not contained in this Study Guide. The essential tables are

Lot size - sample size code letters.

Master tables for single sampling - normal, reduced and tightened (3 tables).

Master tables for double sampling - normal, reduced and tightened (3 tables).

Master tables for 7-stage multiple sampling - normal, reduced and tightened (3 tables).

Limit numbers for reduced inspection.

For reduced plans (the final stage ones for double and multiple plans), Re does not equal Ac+1. A result between Ac and Re signals a switch to normal inspection. For example, consider the reduced inspection single sampling plan for Code K, AQL=1%, namely n = 50, Ac = 1 and Re = 4. While on reduced inspection, if two defectives are found the lot will be accepted but a switch to normal inspection will take place.

The following steps are recommended for obtaining a sampling scheme from MIL-STD-105 E tables. Decide on the AQL.

 1) Decide on the type of sampling plan (single or double or 7-stage multiple).

 2)Decide on lot size.

 3)Obtain the sample size code letter for Level II of General Inspection Level (or any other designated level) for given lot size.

 4)Refer to the appropriate master tables to obtain the required normal, tightened and reduced plans using the AQL and the sample size code letter found in Step 4.

 5)Obtain the limit numbers for reduced inspection using the AQL and the number of sample units for the last 10 lots.

 6)Use Appendix A4.4 to get the switching rules.

 7)Obtain the other relevant performance measures such as LQ, ASN, AOQ and ATI curves (not available in the Study Guide)

Example:

To obtain the MIL-STD-105 E scheme for the desired AQL of 0.65% and lot size 2000, one proceeds as follows:

Step 1: AQL = 0.65.

Step 2: single sampling.

Step 3: lot size = 2000.

Step 4: sample size code letter = K.

Step 5: Master tables yield:

normal inspection plan n = 125 Ac = 2 Re = 3.
tightened inspection plan n = 125 Ac = 1 Re = 2.
reduced inspection plan n = 50 Ac = 1 Re = 3.

Step 6: Limit number for reduced inspection = 4 for AQL = 0.65 and the number of sample units for 10 lots = 1250.

Steps 7 & 8: Consult MIL-STD-105 E or ANSI/ASQC Z1.4 standard tables.

The scheme starts with normal inspection for the first lot and the switching rules shall apply from then on. If one fails to apply the switching rules and uses only normal plans, protection to the consumer will be lost. Consulting supplementary tables and graphs of the standard may also be necessary in order to have some idea of the ASN, AOQL etc.

MIL-STD-105 E contains OC curves for individual sampling plans only. The OC curve of the scheme, ie the steady state or composite OC curve after implementing the switching rules, is not available in the standard.

The civilian version of the MIL-STD-105 E is the international standard: ISO 2859:1985-91 (also BS (British Standards Institution): 6001:1989-91), Sampling Procedures for Inspection by Attributes which corresponds to MIL-STD-105 E. The ISO standard 2859:1985-91 includes the composite OC curves and modifies the rule for discontinuation of inspection to '5 lots not being accepted while on tightened inspection'.

TABLE FOR SAMPLES SIZES, MIL-STD-105D

SINGLE SAMPLING PLANS FOR NORMAL INSPECTION (TABLE IIA OF MIL-STD-105D)

SINGLE SAMPLING PLANS FOR TIGHTENED INSPECTION (TABLE IIB OF MIL-STD-105D)

SINGLE SAMPLING PLANS FOR REDUCED INSPECTION (TABLE IIC OF MIL-STD-105D)

Flexible tube packaging technology

Tube neck shoulder

Tube capacity and diameter

Tube layer specification