Vol. 3, No. 1, January 2019


Critical aspects of machining process capability

for automobile spare part manufacturing (VI) – Testing & Analysis

When it comes to purchasing machined parts, it is important to evaluate the machining process capabilities of your suppliers.

The most critical elements that assure a sound machining process include people, tooling, material, process control, environment, testing, recording and marking.

When you inspect or just visit your machining suppliers, the following is a list of questions you’d need to check with the suppliers on their testing and analysis process to determine the level of their capabilities.


Are measuring and gauging tools available on-site? Are the tools periodically tested to be within acceptable limits?


Check the log book of the on-site tools to determine if the records shown are within the acceptable limits and if Measurement System Analysis (MSC) has been conducted.


Have the process inspectors rigorously verified and properly recorded first article inspections, process inspections, and process records according to the inspection instructions?


Are operators immediately notified by the inspectors and instructed to make corrections when deviations are discovered in process parameters or product requirements?


Are testing done and properly recorded by inspectors and operators on process characteristic parameters?


When defective items are discovered, are they properly marked, separated, evaluated and processed according to the requirements? Are major quality issues immediately reported? Check 8D reports if necessary.


Are quality control charts used for key processes? Is Statistical Process Control (SPC) applied?


Have out-of-tolerance products been analyzed and corrective measures provided?


Are all issues reported previously corrected and closed?

By Felix SS YUAN


Brake Caliper

Caliper is a critical safety part on wheels. Although their failures are rare, vehicle operators should carefully use and check these safety parts based on the manufacturers' manuals.

Primary failure modes:


Leaking, due mainly to sand holes, porosity (with nitrogen and hydrogen) & loose tissues during casting, and nonconformities in cleanness, measurement and geometrical tolerance as well as protection in machining;


Sluggish, due mainly to issues in the casting process and materials especially for the key components of caliper body, piston, sealer and pin, as well as issues in machining and surface treatment.

Key preventive measures:

1. Strict incoming material inspections and recording;
2. Adjust and optimize casting and machining processes;
3. Monitoring the hardness;
4. Periodically conduct type testing;
5. Also test performance and durability.

When driving downhill on a long slope, vehicles with slow descent functions are recommended to make use of the braking capability of the engines. With regular vehicles purely applying calipers for speed control, abnormally high braking power is necessary, causing stress to the braking systems which could lead to permanent damages to the caliper and other parts in the systems as well as serious risks for the vehicle operation.



Quality Assurance (QA) vs. Quality Control (QC)

People involved in quality management quite often refer to their activities and functions as quality assurance (QA) or quality controls (QC). When international buyers deal with their Chinese procurement operations, the effective implementations of QA or QC are also always on their mind when it comes to quality.

While QA and QC are sometime used interchangeably, QA typically refers to activities during the process to assure the products and services meet the quality standards and requirements, and QC typically refers to activities to detect quality defects of the products produced and services delivered, also based on the quality standards and requirement.

QA therefore is process-oriented aimed at defect preventions and QC is product-oriented aimed at defect identifications.


Cost of raw materials:

Exchange rates:

USD/RMB: 1:6.84

EUR/RMB: 1:7.81

RUB/RMB: 1:0.10

January 2019

The above information is for reference only


It is that time again, the Chinese New Year of 2019!

Tuesday, 5th February, marks the beginning of the Year of the Pig, according to the Chinese Zodiac, and it is also the start of the traditional 15-day Spring Festival celebrations.

The annual Spring Festival is the most important traditional holidays for the Chinese. People living and working away from their home towns will always travel back to join the whole families for the celebration. For workers from far-away rural areas, this is usually the only time during the whole year when they get to see their parents or children.

While people in the rural areas do enjoy the 15-day holiday period, those working in the cities will typically get a 7-day holiday. Many organizations and companies would extend the holiday to 10 days, but factories tend to have a shorter period.

Productions at most factories will be suspended during the holidays and since factories and offices are always understaffed before and after the holidays, normal productions, deliveries, and shipments could be disrupted for up to a month.

SHENTOU SUPPLY CHAIN MANAGEMENT CO. LTD. is a Shenzhen, China, based company serving international automotive clients in the implementation of their China strategies and programs. CHINA AUTOMOTIVE SUPPLIER QUALITY MANAGEMENT BRIEFING is a monthly newsletter published by Shentou to address the specific and unique quality challenges and concerns international automotive companies face with suppliers in China. Comments are welcome at Click here to subscribe.

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