So to summaize, quality control is usually done according to the acceptance quality limit( AQL) and AQL sample sizes as described in ISO 2589-1 or its equivalents. Limits for the maximum number of defective goods are determined by you and depend on many factors. Different limits should be set for minor, major and critical defects. Sample sizes are based on the inspection level (General Inspection Levels I, II, III) you want or need product size.
Such parameters are set for each of the different methods of quality control carried out, as explained in the next section.
C. Quality control method: Pre-production inspection
During the pre-production inspection, the third-party inspector inspects the raw materials which the manufacturer will use to produce the end product.
The PPI can also cover semi-finished products for which production has started but are not finished yet.
A PPI is beneficial whenever you work with a new supplier, especially if the project is a large one with critical delivery dates. It is also important when you suspect your supplier has sought to cut costs by substituting cheaper materials before production.
Furthermore, the PPI can reduce communication issues between you and your supplier regarding shipping dates, production timelines, quality expectations and so on.
Ø A good understanding of production schedules.
Ø The ability to anticipate potential issues that could affect project timing or product quality.
Ø Assurance that your requirements will be fulfilled.
Ø Assurance regarding raw material quality and product components.
D. Quality control method: During-production inspection
During the during-production inspection (DPI or DUPRO) the third-party inspector inspects a prescribed amount of the finished products after 15% – 70% of the products are completed. This percentage depends on the order quantity and risk level of the product and manufacturer.
The inspector checks the products on appearance, functionality, color, packaging, quantity and so on.
Defects found during the DPI may be noted in a corrective action plan (CAP) and corrective actions can be taken with minimal disruption to production, which therefore leaves the manufacturer with a bit of wiggling room.
DPIs can be done as a follow-up when problems with quality are found during a pre-production inspection. Problematic batches found during this PPI will be re-checked for defects during the DPI to confirm such problems have been fixed.
If the inspector finds a defect rate higher than the required AQL limits the inspection will be reported as FAILED, if the defect rate falls within the required AQL limits the inspection will be reported as PASSED.
The advantages of doing a DPI include:
Ø Quality and compliance to specifications is maintained throughout the production process.
Ø Any issues can be detected at an early stage and corrected promptly.
E. Quality control method: Pre-shipment inspection
The most common method of quality control is the pre-shipment inspection (PSI).
During this pre-shipment inspection, units are randomly selected from all batches of your order. This is done when production has been completed to a certain percentage.
During the pre-shipment inspection (PSI) the third-party inspector inspects a prescribed amount of the finished products before they’re loaded onto the container.
The inspector again checks the products on appearance, functionality, color, packaging and quantity, etc. The inspector notes down all of his or her findings and publishes an inspection report.
This inspection generally takes place at the manufacturer’s premises or the harbor.
As is the case with a DPI, If the inspector finds a defect rate higher than the required AQL limits during the PPI the inspection will be reported as FAILED, and if the defect rate falls within the required AQL limits the inspection will be reported as PASSED.
According to SGS — one of our partners — A pre-shipment inspection:
Ø Assures you of the quality, quantity, marking, packing and loading of your shipments;
Ø Helps you ascertain that your goods are handled safely and correctly;
Ø Helps you ensure that your goods arrive at their place of destination in compliance with technical specifications, quality standards and contractual agreements.
F. How quality control can be done more effectively
Many companies still use paper for their audit processes, but this makes it difficult to do follow-ups and glean insights from the information collected.
Digital records are thus an advantage.
Digitalization also boosts standardization. Products that are produced simultaneously in different factories still need to be identical when they reach retail, and the risk of accidental variations is higher without standardization and proper quality management.
A cloud-based quality management system keeps all parties on the same page with centralized information such as audit results that are accessible to everyone involved.
Furthermore, it is next to impossible for a sourcing executive to make decisions purely on gut instinct, with all the elements involved in the supply chain.
There is an increasing need for companies to transition from subjective to objective decision-making which means outsourcing some activities to AI.
People, of course, still have a place in strategic planning, but by leveraging cloud-based compliance management software, executives can save time and come to better informed, KPI-driven conclusions.