Corrective and preventive action ISO 9001
Clause 4.14, which serves as the basis for quality improvement, is one of the most important clauses of the ISO 9001 standard. The 1994 revision has made the clause more comprehensive in that. It also covers preventive action, and the effective handling of customer complaints and reports of product nonconformities.
It will be impracticable for manufacturing enterprises experiencing numerous defects and nonconformities during the manufacturing process to investigate individual nonconformities for the purpose of taking corrective action. Taking this situation into consideration, the standard specifies that “Any corrective or preventive action taken to eliminate the causes of actual `or potential nonconformities. It shall be to a degree appropriate to the magnitude of problems and commensurate with the risks encountered. “As a general guide, corrective action can be considered in the following cases :
- Identification of a major conformity.
- When a large number of minor nonconformities of a similar nature are observed.
- Non-compliance observed during an internal audit or a third-party audit.
- Repeated customer complaints
- The recurrence of a problem with a process or activity.
- Major defects or field performance problems reported by the service department.
- Nonconforming deliveries from vendors or subcontractors.
The first step an enterprise must take to determine the corrective action needed is to carry out an investigation. The standard needs the supplier to investigate the causes of nonconformities in the product, process and quality system and to record the results of the investigation.
In a manufacturing environment, investigation involves an analysis of inspection records and test data on materials as well as an examination of tooling and the process capability of manufacturing equipment. A number of statistical techniques such as stratification, the Ishikawa diagram and fault tree analysis can be used for the investigation. The choice of these techniques would depend on the complexity of the problem.
In engineering industries, investigators should be on the lookout for the typical causes of nonconformity. These are listed below.
Design and specifications
- Vague or insufficient manufacturing particulars or illegible drawing prints.
- Impractical design or incompatible components and assembly tolerances.
- The use of obsolete drawings.
Machinery and equipment
- Inadequate process capability
- Incorrectly designed tooling
- Worn tools, jigs or dies
- Non-availability of gauges or measuring equipment
- Poor maintenance of machines
- Equipment affected by environmental conditions such as temperature and humidity.
- Use of untested materials
- Mixed-up materials
- Substandard material accepted on concession because the right material is not available.
Operating and supervisory staff
- Operator does not possess adequate skills for operating process equipment.
- Operator does not understand the manufacturing drawing or instructions related to the process.
- Machine setter does not know how to set the machine correctly.
- Careless operators and inadequate supervision.
- Undue haste by the operator to achieve quantity targets.
Process control and inspection
- Inadequate process control
- Non-availability of proper test equipment
- Test equipment out of calibration
- Vague inspection and testing instructions
- Inspectors do not possess the necessary skills
Evaluation of corrective measures
If the analysis of a detect-causing process is carried out in sufficient depth, the cause will itself suggest the remedy. Some remedies (e.g., replacement of an obsolete drawing, calibration equipment) may be quite simple and can be applied straightaway. Other remedial measures may require considerably more thought. For instance, it may not be feasible to replace a machine that is found to be incapable of processing to the specified tolerance, other measures may therefore have to be considered before a final decision is made. The possible measures contain :
- Alternative method of manufacture
- Selective assembly
- 100% inspection of affected components before assembly to screen out those that are defective.
- Redesign of the component to provide for wider tolerances.
During this stage, all the departments concerned should be consulted to get their views on various methods of preventing defects. The decision on the remedial measures to be adopted will depend on a comparison of the practicability and economics of the various alternatives.
preventive action reduces the need for taking corrective action and is therefore preferable to the latter. The objective of the standard in requiring procedures for preventive action is to provide a means for detecting any deterioration in processes, work standards and systems and thus to prevent the occurrence of a nonconformity. The deterioration may appear trivial on a case-by-case basis, but it may have a significant cumulative effect on the quality of the product in the long run.
Establishing the need for preventive action
The need for preventive action can be brought out by an analysis of the following information :
- Data on process trends
- Records of concessions
- Customer complaints
- Inspection and test records
- Design reviews
- Performance reviews of vendors and subcontractors
Implementation and documentation of corrective and preventive measures
Most corrective and preventive measures in manufacturing enterprises involve changes or improvements in one or more of the following :
- Process, equipment, tooling or test equipment
- Design drawing, specification, document control
- Shape, condition or composition of input material
- Process procedures, work instructions or inspection methods
- Training of operators, inspectors or supervisors
Handling customer complaints
The 1994 version of the ISO 9001 standard specifically requires procedures for the effective handling of customer complaints. A company can deal with complaints only if these have been received and recorded. While numerous customers may express their dissatisfaction with a product, very rarely will they put a formal complaint in writing.
Thus, an enterprise wishing to implement the spirit of this clause needs to bring about attitudinal changes in its staff, particularly in its sales department, and to instildiscipline to ensure that all complaints–including those made verbally–are recorded so that they can be processed to decide and eliminate their causes. The handling of customer complaints can be formalized by setting up a documented procedure covering the following aspects :
- Procedure for noting customer complaints made to the sales staff over the telephone or in writing.
- Registration of complaints and a procedure for acknowledging them to let the customer know that the company cares.
- A form for recording details of the complaint, the name and address of the customer. The covering cash memorandum or other delivery document, date of purchase, etc.
- Procedure for investigating complaints and designating responsibility for follow-up action.
- Procedure for the repair or replacement of defective products, or for compensating the customer in some other manner.
- Monitoring of the complaint-handling process until the complaints are resolved.
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