GB/T 40804-2021 in English

VALID

Short-term capability evaluation of machining processes on metal-cutting machine tools

Issued on:2021-10-11
Implemented on:2022-05-01
File Format:PDF
Delivery:Via email within 5 business days

Price(USD)： $640.00
$621.00

Standard No:	GB/T 40804-2021
Document status:	VALID
Title in English:	Short-term capability evaluation of machining processes on metal-cutting machine tools
Title in Chinese:	金属切削机床加工过程的短期能力评估
Language:	English
File Format:	Electronic (PDF)
Delivery:	Via email within 5 business days
Issued on:	2021-10-11
Implemented on:	2022-05-01
ICS Classification:	25.080.01-Machine tools in general
Chinese Classification:	J50-Machine tool in general
Professional Classification:	GB-National Standard
Related Keywords:	short-term capability evaluation standard short-term capability assessment refers actual process capability index cact=2.0 measurement system capability verification improve s≤80 % capability index calculation bilateral tolerance
Related Topics:	processing short term metal cutting GBT40804 GB/T 40804-2021 Metal Cutting Machine Tool cutting machine tool Metal cutting machine tools (parameters) tRNA processing Standard system in the field of metal cutting machine tools Metal cutting machine tool standard system

《GB/T 40804-2021金属切削机床加工过程的短期能力评估》由TC22（全国金属切削机床标准化技术委员会）归口，主管部门为中国机械工业联合会。

Introduction

Analysis of the core content of the standard

Short-term capability assessment refers to verifying the ability of a machine tool to perform specific processing tasks under statistical confidence by processing 50 test pieces (production cycle <10min), focusing on product characteristics rather than machine tool error sources.

Key Evaluation Process

Stage	Requirements	Technical Indicators
Warm-up Procedure	Ensure Thermal Stability	Thermal Drift≤40μm/h
Measurement System	Resolution≤0.03T	6sg≤0.15T
Statistical Analysis	n≥50 (minimum 30)	Cs≥1.67/RV,s≤80%

Capability Index Calculation

Bilateral tolerance:

Cs = T/(6σ̂) Csk = min[(USL-x̄)/3σ̂, (x̄-LSL)/3σ̂]

Single-sided tolerance:

Upper limit characteristic: Csk = (USL-x̄)/3σ̂

Lower limit characteristic: Csk = (x̄-LSL)/3σ̂

Coordinate measuring machineThe application case shows: When the measuring equipment sg=0.5μm (T=46μm), the actual process capability index Cact=2.0 will be reduced to Cs=1.71 by measurement scatter.

Implementation suggestions

Prioritize the normal distribution characteristics for Cs evaluation, and use RV,s for non-normal distribution characteristics
Roughness measurement needs to be repeated in different areas, and the out-of-tolerance values should be eliminated according to the 16% principle
Multi-spindle machine tools need to evaluate each spindle separately to avoid data confusion

Technology evolution analysis

This standard converts ISO26303:2012 into a national standard for the first time, and strengthens the following innovations:

Clearly define the differences in applicable scenarios between short-term and long-term capabilities
Introduce preconditions for measurement system capability verification
Improve the offset correction model for thermal drift and tool wear

More samples: YD/T 3934-2021 GB 50021-2001(2009) JGJ 94-2008

Sample only — not a preview of GB/T 40804-2021

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