Sampling inspection method for metal stamping parts

Minghe Die Casting Company
5 min readSep 18, 2021

The hardware stamping parts factory has strict inspection standards, which are divided into sampling inspection and full inspection.

Sampling inspection, also known as sampling inspection, is a statistical method and theory for randomly selecting a small number of products (samples) from a batch of products for inspection, and then judging whether the batch of products is qualified or not. It differs from the overall inspection in that the latter needs to inspect the entire batch of products one by one to sort out the unqualified products, while the sampling inspection infers the quality of the entire batch of products based on the inspection results of the products in the sample. If it is concluded that the batch of products meets the pre-specified eligibility criteria, it will be accepted; otherwise, it will be rejected. Therefore, a batch of products deemed qualified after sampling inspection may also contain some unqualified products.

one. Preparation for sampling inspection:
1. After the business contact form comes out, understand the production time/schedule, and initially arrange the inspection time.
2. Get to know the production factory, the type of production, the general content of the contract, be familiar with the production requirements and the quality requirements of our company, and be familiar with the inspection standards, requirements and key points of the inspection in advance.
3. After understanding the general requirements, we must know what are the main defects of the goods inspected. For example, scratches, burrs, deformations, spots and other defects of metal stamping parts. It is necessary to focus on the problems that are prone to occur, to have flexible and adaptable methods, and to be careful and meticulous when inspecting cloth.
4. Know the time when the bulk goods come out, and arrange to arrive at the factory on time.
5. Prepare the necessary instruments for inspection (calipers, micrometers, calculators, etc.) and inspection forms (specific scoring table, key project scoring table, summary table)
And the daily necessities that you need.

two. Perform inspection:
1. After arriving at the factory, preliminary contact with the factory contacts to understand the general situation of the factory, including the system, construction time, number of workers, cnc machine conditions, factory efficiency, etc. Pay special attention to the quality control situation and require them to pay attention to quality and strictly inspect them. Initially communicate with the inspection personnel to get a general understanding of the personnel situation of the factory, such as the finished product department, the quality inspection department, and the person in charge of production.
2. Go to the factory inspection workshop to watch the factory inspector’s inspection, understand whether the factory’s inspection is strict or not, and understand the factory’s inspection basis, inspection system, and treatment methods for some serious defects; at the same time, you can also go to the production workshop to learn about our goods The production situation and other issues are well known.
3. Implement the inspection site (), equipment (such as weight machine, tape measure, calculator, etc.).
4. Under normal circumstances, the opinions of the factory should be solicited and inspections should be arranged first. In general, the platform should be used for medium-thick fabrics,
5. During the inspection, we should ask the factory personnel to cooperate for better operation.
6. Determine the number of inspections:
A. Under normal circumstances, it is necessary to randomly check 10–20% according to the number of different colors.
B. Carry out strict inspection on the sampled goods. If the final quality is qualified, then stop the inspection, indicating that the whole batch of goods is qualified; if there is a small amount of or close to or exceed the scoring standard, then the remaining goods must be randomly inspected by 10%. If the quality of the latter is qualified, then we will downgrade all the unqualified goods in the front; of course, if the quality of the latter is still unqualified, then the whole batch of goods will be regarded as unqualified.
7. Operating procedures for sampling:
A. Control the speed of the metal stamping parts; if it is a platform, you must turn it yard by yard, and you must be careful.
B. According to the quality requirements, according to the scoring standards, the scoring will be strictly performed and filled in the table at the same time.
C. For some special and unclear defects found in the inspection process, you can ask the factory’s quality inspectors on the spot and take samples of the defects.
D. In the inspection process, it must be strictly controlled.
E. In conducting random inspections, we must be careful and meticulous, act logically, and don’t be afraid of trouble.
8. Determine whether all inspection items are missed.
9. The internal quality requires the factory to conduct tests and provide reports,
10. During the inspection process, if there is any quality problem, it should be reported to the company in time to discuss the specific treatment plan. At the same time, the person in charge of the factory should be notified on the spot to coordinate and communicate so that the problem can be solved in a timely and accurate manner.
11. Check the packaging, and check one by one according to the company’s specific packaging requirements.
12. Ask the factory for ship samples, tank samples/batch samples, and factory inspection reports. If you cannot return to the company the next day, you should send the ship samples back to the company in advance, and fax the inspection reports for each day to the company. It should be sent back to the company for early confirmation.
13. Report the progress of production and inspection every day, solicit the company’s opinions and work arrangements for the next day.
14. End the inspection and leave the factory.

three. Fill in the inspection report and summary:
1. Return to the company, fill in the inspection report, the inspection report should include a summary table (approximate evaluation), detailed cloth inspection status table and key project score table, attached sample table, packaging status table, etc., and require relevant personnel Undergo verification.
2. Write the inspection summary and send it to relevant personnel by E-MAIL.
3. Fill out the previous month’s inspection status form on the 5th to 10th of each month and send it to relevant personnel by E-MAIL.

Four. Contents of inspection:
According to different products and different requirements, strict inspection should be carried out. The items to be inspected must be comprehensive, and the details must not be missed. Items that are not or cannot be inspected must be clearly displayed on the inspection report.



Minghe Die Casting Company

Minghe is a global, full-service manufacturer of precision die casting products.