PRIORITIZATION OF IMPROVEMENT ACTIONS IN INDUSTRIAL PRODUCTION: APPLICATION OF THE FITRADEOFF METHOD TO ORDER IMPROVEMENT ACTIONS IDENTIFIED THROUGH THE FAILURES MODES AND EFFECTS ANALYSIS (FMEA)

Zanazzi, José Francisco; Zanazzi, José Luis; Pontelli, Daniel

doi:10.1590/0101-7438.2023.043spe1.00263696

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ARTICLES • Pesqui. Oper. 43 (spe1) • 2023 • https://doi.org/10.1590/0101-7438.2023.043spe1.00263696 copy

PRIORITIZATION OF IMPROVEMENT ACTIONS IN INDUSTRIAL PRODUCTION: APPLICATION OF THE FITRADEOFF METHOD TO ORDER IMPROVEMENT ACTIONS IDENTIFIED THROUGH THE FAILURES MODES AND EFFECTS ANALYSIS (FMEA)

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

The Failures Modes and Effects Analysis (FMEA) method is applied to different activities in order to improve production processes. Its operation allows to analyze failure modes, describe their effects, identify causes and design control systems. In addition to assessing these factors, it contributes to the formulation of various improvement actions; however, it has an intrinsic weakness when it comes to prioritizing these actions. Although recent versions acknowledge that it is convenient to regulate the beginning of the proposed actions, the method does not provide indisputable tools to establish priorities and organize action plans due to the fact that the Risk Priority Level traditional indicator has been questioned. In face of this need, this contribution proposes to complement the application of the FMEA with an individual multi-criteria compensatory method that allows actions to be programmed in a participatory manner to improve their management. This proposal provides an example of a real world application. The results and limitations of this work are presented in the conclusion.

Keywords:
individual multi-criteria decision methods; FITradeoff method; quality systems; prioritization of improvement actions; Failure Modes and Effects Analysis (FMEA)

Process: Manufacture of car springs
Operation	Function. Requirements	Failure modes	Consequences	Cause	Frequency	Improvements proposed
Heating the rod	Rod temperature to melting point	Temperature below specifications	May cause mild problems in the coiling	Fuel (gas) supply problems	1 every 20000	Place a pressure gauge in the gas circuit, which automatically stops the job in the case of excessive variations
Coiling	Space between coils	Very small space	May affect paint and cause cosmetic defects	Large rod diameter	1 every 30000	Install a go-no go gauge before entering the heating furnace, which prevents the treatment of parts with deformations
Coiling	Space between coils	Very small space	May affect paint and cause cosmetic defects	Damaged chuck	1 in 300	Add an optical sensor that checks the chuck and detects possible deformations
Coiling	Outer diameter	Excessive outer diameter	May affect paint. Claims for assembly difficulties	Chuck maintenance	1 in 500	Modify the procedure used for chuck maintenance
Quenching	Sharply reduce spring temperature to harden the surface of the part	Out-of-spec quenching oil temperature	The required surface hardness is not reached	Oil cooling circuit runs with problems	1 every 9000	Change the components of the oil cooling system with high periodicity
Tempering	Reduce stress on the spring surface that originates from tempering	Non-homogeneous temperature profile inside the furnace	Heterogeneity in the surface hardness of the tempered parts	Failure in maintenance of the tempering furnace. Age of the tempering furnace	1 every 10000	Change the tempering furnace
Blasting	Blast the spring surface with steel balls, to extend the service life of the part	Nozzles deformed by use	Parts do not receive the density of impacts needed to achieve the service life required by design	Wear of nozzle material	1 every 25000	Implement a method of checking and maintaining nozzles

Criteria	Definition	Categories
Impact on the Product	Impact of the proposed action on the product. Target to maximize.	Slight
		Minor
		High
		Very high
Impact on the Process	Impact of improvement on the process. Criterion to maximize.	Slight
		Minor
		High
		Very high
Probability	Influence of the proposed transformation to reduce the likelihood of failure occurrence. Criterion to maximize.	Slight
		Minor
		High
		Very high
Cost	Cost of the improvement. Minimization Criterion.	Slight
		Minor
		High
		Very high

Proposed improvement actions	Criteria
Proposed improvement actions	Impact on the Product	Impact on the Process	Impact on Frequency of Failure	Cost
Place pressure gauge to regulate gas pressure	Slight	Minor	Slight	High
Go-no go gauge when entering the heating furnace	High	Slight	Slight	Slight
Optical sensor on the chuck, which detects deformations	Very high	High	Very high	High
Modify chuck maintenance criteria	Very high	High	Very high	Slight
Improve the oil circulation system in the quenching	High	Minor	High	Minor
Change the tempering furnace	High	Minor	Very high	Slight
Implement nozzle check and maintenance in the blaster	High	Slight	High	Minor

Ranking Position	Alternatives
1	[Modify chuck maintenance criteria]
2	[Optical sensor on the chuck, which detects deformations]
3	[Change the tempering furnace]
4	[Improve the oil circulation system in the quenching]
5	[Implement nozzle check and maintenance in the blaster]
6	[Go-no go gauge when entering the heating furnace]
7	[Place pressure gauge to regulate gas pressure]

Sensitivity Analisys
Variation Percentage Values	Impact on the product	Cost	Impact on the Process	Probability
Max	+10%	+10%	+10%	+10%
Min	-10%	-10%	-10%	-10%

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E-mail: sobrapo@sobrapo.org.br

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[1] *Corresponding author

Analyzed problem	A productive process leader has to plan improvement actions resulting from the FMEA analysis, so that the team executes them. The FMEA has difficulties to discriminate the actions according to the adopted criteria, the indicators and their manipulation.
Context of the problem	The FMEA is a required tool by quality management systems. Clients, parent companies, managers, among other actors, request its implementation and require reports on the progress made. The operators of the process collaborate with the leader in its elaboration.
Available time	FMEA reviews are conducted regularly by the work groups between 6 and 12 months after the last analysis. In general, the term for the implementation of corrective and preventive actions is between 15 and 30 days. The term for improvement proposals is around 2 months. After implementation, its monitoring is continuous and results must be recorded.
Main objective	Prioritizing actions resulting from the FMEA in a systematic way, where aspects that the tool does not value are incorporated, so that it allows selecting a reduced number of activities to facilitate its implementation.
Specific objective	- Incorporating criteria that allow the proposals to be prioritized.
	- Evaluating the performance of actions according to the defined criteria.
	- Planning improvement actions.