The three pre steps of FMEA Analysis are explained below:

Step 1  -  Severity

In this step, all failure modes associated with product functioning and their effects are determined.  Corrosion, deformation, and electrical short-circuits are some examples of failure modes.  Since failure modes lead to a chain process, it is necessary to list each failure mode according to its function and in technical terms.  Then failure effect for each failure node is analyzed.  Noise, injury to user, and degraded performance are some examples of failure effects.  A Severity Number (S) is assigned to each failure effect ranging from 1 (no danger) to 10 (critical).  This helps in prioritization of failure modes and effects.  If a failure effect has a severity rating of 9 or 10, then it would cause injury to user or end up in litigation.  Such failure modes are immediately eliminated and the design is changed.

Step 2  -  Occurrence

In this step, the causes of each failure and its frequency are identified and documented in technical terms.  An earlier documentation for similar processes would be of value here.  Examples of failure causes are excessive voltage, improper operating conditions, erroneous algorithms, etc.  Failure causes are weaknesses in design.  An Occurrence Ranking (O) is assigned to each failure mode, ranging from 1 to 10.  It can also be expressed in %.  Non-safety failure modes have ranking >4, if their Severity Number are 9 or 10, they have ranking >1.  All these cases demand determination of action.  Occurrence Ranking is based of the product and specifications of customer.  This step is known as the detailed development category of FMEA.

Step 3  -  Deduction

In this step, the actions determined are tested for their efficiency.  Design verification is done, and proper inspection methods are chosen.  To do this, the engineer should look at the current system controls and assess their ability to prevent failure modes or detect them before it moves over to customer.  The testing, monitoring, analysis, and other techniques used in similar system controls to detect failures can be identified.  A Detection Number (D) is assigned to the inspections or planned tests according to their ability to detect or prevent failures.  D measures the extent of risk of a failure escaping detection.  Thus, a higher ranking of D indicates the chance of failure detection is low.

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A good example of implementation of kanban system is the ‘three-bin’ system for parts supplied (it is assumed no in-house manufacturing is available).  In this system, there is a bin in the factory floor (demand point), one bin at the factory store, and another bin in the suppliers’ store.  These bins contain the kanban card which is removable, and containing product details and other information.

When a demand is faced for parts, the factory floor bin gets empty, which is returned to factory store along with its kanban cards in exchange for full bin and kanban cards.  The factory store then presents its empty bin and kanban cards to the suppliers’ store and gets full bin with kanban cards in turn.  This completes the system, which is like a loop.

This system ensures that only the exact needed amount is provided, with just one spare to regulate the supply, with room for uncertainty in supply and transport.  It also ensures the process never runs out of product.  You have to calculate the number of kanban cards needed for every product, in order to implement a good kanban system.  In this system, the colored board system (Heijunka Box) is used for holding kanban cards.

Nowadays, many manufacturing organizations have switched over to E-Kanban systems, which have eliminated errors in manual entry, loss of cards, and similar problems.

E-Kanban systems can also be integrated into ERP (Enterprise Resource Planning) systems, which enable real-time demand signals across supply chains and clear view of the processes.  The data gathered can be utilized for optimization of inventory levels through enhanced tracking of replenishment times and supplier lead.

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