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潜在失效模式及后果分析(FMEA)
集体讨论
什么情况下会导致一次培训失效???
FMEA 的定义
潜在失效模式及后果分析(Potential Failure Mode and Effects Analysis)是一种系统化的可靠性定性分析方法。通过对产品/过程各组成部分进行事前分析,发现、评价产品/过程中潜在的失效模式及起因/机理,查明其发生的可能性及对系统的影响程度,以便采取措施进行预防。
失效(Failure)
实体全部或部分失去了完成其功能的能力。其中实体是指产品、过程或系统。
潜在
有可能发生有可能不发生的事情。
Potential Failure Mode and Effects Analysis
(FMEA)
Discussion
What may lead the training failed?
Definition of FMEA
Potential Failure Mode and Effects Analysis (FMEA) can be described as a systemized and qualitative analysis method for reliability. The purpose of FMEA is to Recognize and analyze the potential failure of a product/process, evaluat its effects and probability before the event, identify actions which could eliminate or reduce the chance of the potential failure occurring.
Failure
It is a manner which the things could fail to meet the intent partly or wholely. The things may the product, process or system.
Potential
The failure may happen or not.
FMEA 的类型
SFMEA ——是针对产品开发、过程策划进行的FMEA。通过系统、子系统、分系统不同层次展开,自上而下逐级分析,更注重整体性、逻辑性。
DFMEA ——是针对设计过程进行的FMEA,主要在于识别和消除产品及每一零部件的设计缺陷。
PFMEA——是针对工艺过程进行的FMEA,目的在于识别和消除制造/服务过程中每一环节的潜在隐患。
FMEA 应用
– 50年代初期,美国Grumman公司第一次把FMEA思想用于一种战斗机的操纵系统的设计分析,取得较好效果,以后逐渐推广
- 60年代中期用于美国航天工业(阿波罗)
- 1974年用于美国海军(1629号军标)
- 1985年IEC公布了FMEA标准: IEC812,
- 这个标准被我国等同采用为GB 7826-87
- 《系统可靠性分析技术,失效模式和效应分析(FMEA)程序》
Types of FMEA
SFMEA——It is performed to improve product development and process planning. Through different levels launch of the systems, the subsystems, and components to analyze from top to bottom. And it stresses the integration and logicality.
DFMEA——It is performed to improve system design. It is used for identifying and dispelling the design weakness of products and components.
PFMEA——It is performed to improve manufacturing process. Its purpose is to identifying and dispelling the potential hidden defects of the manufacture/service process.
Application of FMEA
- In the early 50's, the Grumman used the FMEA to develop the operation system hof a battleplane for the first time. It obtained good results and then became popular.
- It was used for the aerospace industry of USA (Apollo) in the mid – seventies.
- It was used for USN in 1974(1629 Military Standard)
- The IEC realeased FMEA standard in 1985: IEC812
- This standard was adopted in our country as GB7826-87
- System Reliability Analysis, Failure Mode and Effects Program
FMEA 的应用与发展
QS-9000 质量体系要求—美国汽车工业行动集团(AIAG)
VDA6.1 质量体系审核—德国汽车汽车工业联合会(VDA)
ISO/TS 16949质量管理体系要求—国际汽车特别工作组 (IATF)
均将进行FMEA分析作为质量管理体系的重要内容。
何时进行 FMEA
情形1:用于新产品设计、新技术应用和过程设计时。FMEA覆盖了全部产品设计、技术应用和过程设计。
情形2:用于现有的设计或过程修改时。FMEA的范围集中于对设计或过程更改的部分。
情形3:用于将现有设计或过程用于新的环境、场所时。FMEA的范围集中于新环境或场所对现有设计或过程的影响。
Application and development of FMEA
QS-9000 Quality System Requirements—AIAG
VDA6.1 Quality System Auditing—VDA
ISO/TS 16949 Quality Management System Requirements—IATF
FMEA is considered as an important matter of quality management system.
When to put up FMEA
Case1: New designs, new technology, or new process. The scope of the FEMA is the complete design, technology, or process.
Case2: Modifications to existing design or process. The scope of the FMEA should focus on the modification to design or process, possible interactions due to the modification, and field history.
Case3: Use of an exsiting design or process in a new environment location, or application. The scope of the FMEA is the impact of the new environment or location on the exsiting design or process.
FMEA 在APQP中的地位和作用
FMEA 的流程
When to do FMEA during APQP process
DFMEA
特殊特性清单
过程流程图
PFMEA
Control plan
作业指导书
DFMEA
Bill of special characteristics
Process flow chart
PFMEA
Operation instructions
Requirements of customer
Preliminary bill of special characteristics
Flow of FMEA
定义
产品
/
过程
List potential
Failure Modes
Evaluate the
Probability of the
Failure
Form the RPN
Risk in sorting
Document the
Process
Define the
Product and
Process
Define the
Potential
Cause/mechanisms
Of Failure
Evaluate the
Potential effects
of the failure
to the customers
FMEA 的特点
1 一种事前行为
2 结构化的方法
3 一个循环的过程
4 一种多方论证的产物
- 有专人负责
- 结合集体的智慧
设计
质量
制造 共同评审
服务
可靠性
顾客
输出
FMEA
责任工程师
输入
设计
质量
制造
服务
可靠性
Characteristic of FMEA
1. An action of befor-the-event
2 .Structuring method
3 .A cycle process
4 .A result of multidisciplinary approach
- A specific engineer is assigned to be responsible for it
- Collective wisdom
Input
Design
Quality
Manufacture
Service Review together
Reliability
Customer
Output
FMEA
Responsible engineer
Design
Quality
Manufac
Service
Reliability
子项目
要求
系统
潜在失效模式
潜在失效后果
严重度S
级别
潜在失效起因/机理
频度O
现行设计控制
(预防)
现行设计控制
(探测))
探测度D
R
P
N
建议
措施
责任及目标完成时间
措施结果
采取的措施
S
O
D
RPN
会有什么问题?
- 无功能
- 部分功能/性能
- 过强/功能降级
- 功能间歇
- 非预期功能
后果是
什么?
有多
糟糕?
起因
是什么?
发生的
频率如何?
怎样能
得到预防
和探测?
该方法在探测
时有多好?
能做些什么?
- 设计更改
- 过程更改
- 特殊控制
- 标准、程序或指南的更改
功能、特性或要求是什么?
Subsystem
Function
requirements
Potential failure modes
Potential effects of failure
S
e
v
C
l
a
s
s
Potential cause(s)/
Mechanism
(s) of failure
O
c
c
u
r
Current design controls
(Prevention)
Current design controls
(Detection)
D
e
t
e
c
R
P
N
Recommended action
Responsibility & target completion date
Action results
Actions taken
S
O
D
RPN
What are the Functions、Features or Requirements ?
What can go wrong?
- No function
- Partial/Over/
Degraded Function
- Intermittent Function
- Unintended Function
What are the effects?
How often does it happen?
What are the causes?
How bad is it?
How can this prevented and detected?
How good is the method at detecting it?
What can be done?
- Design changes
- Process changes
- Special control
- Changes to Standard, Program or Guide
潜在设计失效模式及后果分析(DFMEA)
Potential Design Failure Mode and Effects Analysis
谁来做:负责产品设计的工程师/小组
DFMEA中顾客的定义:
1)最终使用者
2)更高一层的设计师或总设计师
3)装配、生产和服务工程师
DFMEA需要准备的资料
─ 由QFD得到的设计要求;
─ 产品可靠性和质量目标;
─ 产品的使用环境;
─ 类似产品的失效分析(FMA);以往类似产品的DFMEA;
─ 初始工程标准;
─ 初始特殊特性明细表;
─ 功能框图。
Potential Design Failure Mode and Effects Analysis
(DFMEA)
Who to do:Design responsible engineer/team
Customer defined:
1)End user
2)The design responsible engineers/team of vehicle or higher level assemblies
3)Engineers responsible for assembly, manufacturing and service.
The material prepare for DFMEA
─ Design requirement from QFD;
─ Reliability and quality goals;
─ Using environment;
─ Failure modes analysis of similar product;
─ DFMEA of similar product before;
─ Preliminary engineering specification;
─ Preliminary list of special characteristic;
─ Functional block diagram.
DFMEA在体现设计意图时,还应保证制造、装配、维修、服务能够实现设计意图。
例如:
─ 必要的拔模(斜度)
─ 要求的表面处理
─ 装配空间/工具的可接近
─ 要求的钢材强度
─ 过程能力/性能
─ 便利的维修工具
─ 简便的诊断方法
─ 材料的可回收性,是否满足环保要求
DFMEA的第一步
The DFMEA addresses the design intent and assumes the design will be manufacturing, assembly, maintaining and service to this intent.
e.g.:
─ Necessary mold drafts
─ Limited surface finish
─ Assembling space/access for tooling
─ Limited hardenability of steels
─ Process capability/performance
─ Tool access
─ Diagnostic process
─ Materials recycling, whether meet the requirements of environmental protection
The first step of DFMEA
希望、不希望
顾客的期望
(
QFD
)
车辆要求的文件
产品的制造
/
装配
/
服务
/
回收要求
希望、不希望
顾客的期望
(
QFD
)
车辆要求的文件
产品的制造
/
装配
/
服务
/
回收要求
Expected、unexpected
Customer expectation
(
QFD
)
Manufacturing /Assembly/
Service/Campaign requirements of
Products
The reauirements
Vehicle
The more definite of
Expectation characteristic is defined
the easier to identify the failure mode
DFMEA的第二步
DFMEA的几个基本概念
1、项目/功能
─ 简要说明设计意图要求的功能,包括环境信息。如果项目有多种功能,应分别列出。
─ 可靠性:是指产品在规定的条件下和规定的时间内完成规定功能的能力。不能完成规定的功能就称失效。
─ 功能:设计这个系统/子系统/零部件做什么?设计要求?设计意图?
─ 一个零部件(或子系统/系统)的功能往往是多项的。这种情况下,必须把所有的功能全部列出,不能遗漏。
The second step of DFMEA
System:Flashlight
Lamp-chimney
A
On
/
Off
C
Lamp assembly
D
Pole plate
E
Battery
B
Spring
F
2
4
3
1
5
5
Limiting condition of workplace
Temperature:
-20~160F
corrosion resistance:
Specification
B
Impact:
External material:Dust
Humidity :
0~100RH
Flammability:
1.
Skip fit
2.
Rivets
3.
Threaded
4.
Snap fit
5.
Comperssion fit
Out of this
FMEA
C
2
4
3
1
5
5
Fall down from 6 feet
Basic concept of DFMEA
1. Item/function
─ Enter, as concisely as possible, the function of the item being analyzed to meet the design intent. Include information regarding the environment in which this system operates. If the item has more than one function with different potential modes of failure, list all the functions separately.
─ Reliability: It is the capability of the products to accomplish the required function within the specified conditions and the given time. It is called failure if the purposed function could not achieve.
─ Function:What is the purpose to design the system/subsystem/ component? The requirements of the design? The design intent?
─ If the component (or subsystem/system) has more than one function, list all the functions separately.
示例:激光笔功能框图
激光芯版
外部圆形镜片
圆桶型管
电池后盖
功能:
1. 提供电源
2. 激光聚焦
3. 提供当前的电源路径
功能:
1. 密封激光
2. 输出镜头
3. 遮蔽灰尘
4. 必须易于卸装
功能:
1. 密封
2. 安装电池
3. 提供电源
4. 激光芯安装
5. 易于抓握的激光笔表面
6. 抓握的提示标签
功能:
1. 密封
2. 安装电池
3. 提供电源
4. 必须容易卸拆
2、潜在失效模式
─ 对每个项目和功能,列出每一个潜在的失效模式。
─ “潜在”是指可能发生也可能不发生;失效就是丧失功能。而失效模式就是失效的表现形式。
─ 应用规范化、专业化的术语来描述失效模式。常用的有两大类失效:Ⅰ类失效、Ⅱ类失效。
e.g.: Functional block diagram of the laser pen
External circular glass
Laser chip
Cylindrical tube
Aft closure of battery
Function:
7. Airproof
8. Install the battery
9. Power supply
10. Install the laser chip
11. The prehensile surface of laser pen
12. Grasping cue sign
Function:
5. Seal laser
6. Output shot
7. Dust proof
8. Easy to assemble and unassemble
Function:
4. Power supply
5. Focusing of laser
6. Current power supply
Function:
5. Airproof
6. Install the battery
7. Power supply
8. Easy to disassemble
2. Potential Failure Mode
─ List each potential failure mode for the particular item and item function.
─ “Potential”is that the failure could occur, but may not necessarily occur; failure is the loss of function. The failure mode is the manner of failing to meet the design intention.
─ Potential failure mode should be described in “physical” or technical terms. There are two categories of failure, those are: failureⅠ, failure Ⅱ.
示例:失效模式的种类
─ Ⅰ类失效,指的是不能完成规定的功能,如:
Ø 突发型:断裂、开裂、碎裂、弯曲、塑性变形、失稳、短路、断路、击穿、泄露、松脱等等。
Ø 渐变型:磨损、腐蚀、龟裂、老化、变色、热衰退、蠕变、低温脆变、性能下降、渗漏、失去光泽、褪色等等。
─ Ⅱ类失效,指的是产生了有害的非期望功能,如:
Ø 噪声、振动、电磁干扰、有害排放等等。
3、潜在失效后果
─ 是指失效模式可能带来的对完成规定功能的影响,以致带来顾客的不满意和不符合安全和政府法规。
─ 要运用失效链分析方法,搞清楚直接后果、中间后果和最终后果。
─ 站在顾客的角度发现或经历的情况来描述失效的后果(顾客可能是内部的顾客,也可能是外部或最终顾客)。
e.g.:Types of failure modes
─ FailureⅠ, It means the function that can't accomplish stipulation,for example:
Ø Slugtype:Fractured, fissured, spalt, bendt, plastic deformation, astable, short circuit, open circuit, hole, leaking and loosened, etc.
Ø Gradual change:Abrasion, corrosion, fissuration, degradation, discoloration, heat fade, creep, cold embrittlement, performance degradation, leakage, devitrification and depigmentation, etc.
─ FailureⅡ, It means having brought deleterious unexpected function, for example:
Ø Noise, buffeting, electromagnetic disturbance and emission, etc.
3. Potential effect(s) of failure
─ It is defined as the effects of the failure mode on the function, and ultimately leads to customer dissatisfaction, impact safety or noncompliance to regulations.
─ Use the analytical method of failure chain to identify the immediate consequence, midst consequence and final consequence clear.
─ Describe the effects of the failure in terms of what the customer might notice or experience (the customer may be an internal customer as well as a external or the ultimate end user)
失效后果可以从以下几方面考虑:
─ 对完成规定功能的影响;
─ 对上一级系统完成功能的影响;
─ 对系统内其他零件的影响;
─ 对顾客满意的影响;
─ 对安全和政府法规符合性的影响;
─ 对整车系统的影响。
案例
某公司是生产轻型商用汽车钢板弹簧的企业,年产载重量为三吨的商用车钢板弹簧20万套。产品基本结构为四片弹簧,每片厚度为9mm。从目前市场反馈的情况看,出现的主要问题是:
1)弹簧片断裂,大约每年出现1000次;
2)卷耳早期磨损,每年大约出现1800次
现在该公司准备开发用于五吨车的钢板弹簧
针对现状对将要开发的产品进行DFMEA分析
The effects of failure are considered as follow:
─ The effects on completing the defined function
─ The effects on completing the function in a higher level
─ The effects on the other components of the system
─ The effects on the customer satisfaction
─ The effects on safety and compliance to regulations
─ The effects on entire vehicle system
Case
A company manufactures the leaf spring for light commercial vehicle whose payload is 3 ton. The yield is 0.2 million sets annually. The basic structure of the product is four pieces of spring, the thickness of each one is 9mm. Fed back from the market, and the main problems are the followings:
1) fracture of the spring strip, which appears about 1000 times annually;
2) earlier abrasion of the spring ear, which appears about 1800 times annually
Now the company is prepared to develop the leaf spring used for vehicles of 5 tons
How to develop DFMEA for the new product?
潜在失效模式及后果分析
(DFMEA)
系统 FMEA编号:
子系统 页 码:第1页 共3页
部件 设计责任: 编制者:
车型年/车辆类型: 关键日期: FMEA日期(编制): (修订)
核心小组:
项目
功能
潜在失
效模式
u
潜在失
效后果
严重度
级
别
t
潜在失效
起因/机理
频度
O
t
现行设计控
制预防
u
现行设计控
制探测
探测度
R
P
N
t
建议措施
责任及
目标完成
日期
措 施 结 果
采用的措施
严
重
度
频
度
探
测
度
R
P
N
Potential Failure Mode and Effect Analysis(Design FMEA)
system FMEA Number:
Subsystem Page of
Component Design Responsibility: Prepared by:
Model year(s)/Vehicle(s): Key date: FMEA date (orig.) :(rev.)⑦
Core team:
Item
Function
Potential
failure
mode
u
Potential
effects
of failure
S
e
v
Cl
ass
t
potential causes/mechanisms of failure
O
c
c
u
r
t
current design controls
(prevention)
u
current design controls
(detection)
D
e
t
e
c
R
P
N
t
Recommended actions
Responsibility & target completion date
Action result
Actions taken
S
O
D
R
P
N
1)FMEA编号
填入FMEA文件编号,以便查询。
2)系统、子系统或零部件的名称及编号
注明适当的分析级别并填入被分析的系统、子系统或部件的名称及编号。
系统FMEA的范围
一个系统可以看作是由各个子系统组成的。如:底盘系统、传动系统、内饰系统等。系统FMEA是要确保组成系统的各自系统间所有接口和交互作用以及该系统与车辆其它系统和顾客的接口都要覆盖。
子系统FMEA的范围
一个子系统FMEA通常是一个大系统的一个组成部分。例如,前悬挂系统是底盘系统的一个组成部分。因此,子系统FMEA要确保组成子系统的各部件间的所有的接口和交互作用都要覆盖。
部件FMEA的范围
部件FMEA通常是一个以子系统的组成部分为焦点的FMEA,例如,螺杆是前悬挂(底盘系统的一个子系统)的一个部件。
1)FMEA Number
Enter the FM
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