In the design and production process of any product, it is common to encounter design changes, process modifications, production process adjustments, unplanned production halts and transfers, and other activities. So, how can we ensure that these activities do not affect the quality of subsequent production? This is where the first piece inspection during operation preparation verification and post-halt verification comes into play.
I. Definition of First Piece and First Piece Inspection
Process Change
In the production process, any change in one or more of the 5M1E factors (Man, Machine, Material, Method, Environment, Measurement) constitutes a process change. This includes changes such as personnel shifts, equipment adjustments and maintenance, material and fixture changes, design changes, production halts, etc.
First Piece
The first or the first few products processed on the production line when each shift/line starts production or after a process change. For mass production, the "first piece" often refers to a certain number of samples.
First Piece Inspection
An inspection conducted on the first or the first few products processed on the production line when each shift starts or after a process change. The number of items to be inspected can be determined according to the requirements of different enterprises or customers. Generally, at least 3 to 5 consecutive products should be inspected and approved before continuing to process subsequent products. First piece inspection must be strictly carried out before any change in equipment or manufacturing process, and at the beginning of each work shift.
II. Purpose of First Piece Inspection
The main purpose of first piece inspection in the production process is to prevent products from having batch deviations, repairs, or scrapping. It is a means of pre-controlling the product production process, an important method of quality control in product process, and an effective and essential method for enterprises to ensure product quality and improve economic efficiency.
First piece inspection is conducted to detect as early as possible the factors in the production process that may affect product quality and to prevent batch defects or scrapping. Production can only commence after the first piece has passed inspection, primarily to prevent the occurrence of batch non-conforming products.
Long-term practical experience has proven that the first inspection system is an effective measure to detect issues early and prevent batch product scrapping. Through first piece inspection, systematic issues such as severe wear of fixtures or incorrect installation, reduced accuracy of measuring instruments, misreading of drawings, incorrect materials or formulas, etc., can be identified, allowing for corrective or improvement measures to be taken to prevent batch non-conforming products.
III. Timing/Occasions for First Piece Inspection
At the start of each work shift; when the operator is changed; when equipment or process equipment (including tool changes or grinding); when technical conditions, process methods, and process parameters are changed (such as changes in roughness requirements, converting reaming to boring, changes in feed rate or rotational speed in CNC programs); after using new materials or substitutes (such as material changes during processing); when tank solutions are changed or retested (such as phosphating, nitriding, etc.).
IV. Process Change
In the production process, any change in one or more of the 5M1E factors (Man, Machine, Material, Method, Environment, Measurement) constitutes a process change. This includes changes such as personnel shifts, equipment adjustments and maintenance, material and fixture changes, design changes, production halts, etc.
Requirements for First Piece Inspection
The first piece inspection adopts a three-inspection system: self-inspection, mutual inspection, and special inspection.
Products submitted for inspection must first be "self-inspected" by the operator, then "mutually inspected" by the team leader or colleagues, and finally "special inspected" by the inspector. Only after the product is approved can subsequent products be processed.
Whether the first piece passes inspection should ultimately be confirmed by a dedicated inspector. For products that pass the first piece inspection, the inspector should mark them accordingly and maintain the mark until the end of the shift or batch production (all first piece products must be retained as samples for comparison with subsequent products to see if the process has changed, and marked with a "√" to indicate passing the first piece inspection). If the first piece fails inspection, the causes must be identified, measures taken to rectify the issues, and the product reprocessed and re-inspected until it passes inspection.
V. Main Items of First Piece Inspection
- 1. Whether the drawing number matches the work order;
- 2. Whether the material, blank, or semi-finished product matches the work task order;
- 3. Whether the surface treatment and installation positioning of the material and blank are correct;
- 4. Whether the formula and batching meet the specified requirements;
- 5. Whether the actual quality characteristics of the first piece product meet the requirements specified in the drawings or technical documents.
VI. Standard Process for First Piece Inspection
Subject Content and Scope of Application
This document specifies the requirements and work procedures for the first piece inspection of new products and batch first piece inspection during the company
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