Definition Of Special Characteristics
Special characteristics refer to products or process characteristics that affect the safety of vehicles or processes, comply with government regulations, customer satisfaction or process operation.
Special characteristics require quality planning actions that must be addressed in the control plan.
The selection, identification and control of special characteristics is the process of establishing and using failure mode and effect analysis (FMEA) and existing product design and manufacturing process knowledge to select, identify and control the special characteristics of products and processes.
Characteristics are either special or not. Special characteristics can be classified as critical characteristics CC (∇), significant characteristics SC, operator safety OS or high-impact characteristics HI.
The detailed classification of characteristics is as follows
Product characteristics refer to the quantifiable/measurable physics and chemical characteristics of products, such as size, size, shape, position, direction, texture, hardness, tensile strength, strength, coating, reflectivity, finish, color or chemical properties.
Process characteristics refer to measurable characteristics of process inputs and their interactions that affect process outputs. Examples of process parameters include speed, feed, temperature, chemical concentration, pressure and voltage.
The critical characteristic CC is represented by the inverted triangle symbol (√). It refers to the product requirements (size, functional performance requirements, material specifications, etc.) or process parameters (speed, temperature, pressure, etc.) that can affect the compliance with government regulations and/or safety vehicles and/or product functions.
Critical characteristics require specific manufacturing, assembly, transportation and/or monitoring measures, and are included in the control plan.
The potential critical characteristic YC is identified by DFMEA. Transferred to PFMEA, PFMEA confirms whether the characteristics are critical and whether special control is required.
The Significant characteristic SC refers to the product, process and test requirements that have a great impact on customer satisfaction. Significant characteristics require quality planning actions and must be addressed in the control plan.
The potential significant characteristic YS is identified by DFMEA. PFMEA confirms whether the potential characteristics are significant and the necessity of implementing special control. PFMEA also determines the process characteristics and parameters required for effective delivery of product characteristics.
Operator safety characteristics (OS) refer to those process parameters or product characteristics that may adversely affect the safety of operators or the compliance with government regulations (for example, Occupational Safety and Health Administration [OSHA] requirements, health and safety regulations). These characteristics need to be included in the safety signs. Due to the impact of process on process operators, the severity of these failure modes is 9 or 10.
significant influence characteristic HI refers to the process parameters or product characteristics that may have an adverse impact on the process or subsequent operation, but will not have an adverse impact on customer satisfaction. The characteristics of significant impact shall be emphasized in the quality planning actions, and these actions must be listed in the control plan.
Identification Of Special Characteristics
The identification and management of special characteristics has always been the focus and difficulty in the application of IATF16949 system and five major tools. As one of the methods for identifying special characteristics, FMEA can be classified into special characteristics based on the score of SOD and the experience of the FMEA team.
The following figure shows the identification method of special characteristics in Ford FMEA manual
FMEAHunter Software Automatically Sets Characteristics Classification
1. The FMEA project under FMEA Hunter refers to the global special characteristics classification;
2. In the FMEA project, modify and define the characteristic classification rules in this FMEA;
3. Calculate and set all elements conforming to the rules as specific special characteristics according to the rules;
