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Chapter 5: WA-NRI Case Studies

This chapter is dedicated to present some examples of using R4All platform to perform Warranty Analysis for Non-Repairable Items (WA-NRI).

5.1 Case Study 1: Home Appliances Manufacturer

A manufacturer of home appliance products is now tracking the performance of an important item (component) from a new product released in the month of January. As it is a new product, they started with 2,000 units/month and then grew to a rate of 10,000 units/month, and now they will maintain this rate of production.

The company is offering a 1-year warranty for this product. Based on the warranty returns report for six months of life for this component, the company wants to determine: the forecast of returns for the next 6 months of this component; the total amount of items to be returned in one year of warranty; and other information, such as warranty budget for this year, reliability curves, etc.


Filling the Nevada Chart with the quantity produced of each month and the returns referent to each lot:


The warranty analysis automatically generates the data sheet to be used by the life data analysis. The image below shows the LDA tab filled up with the time to events, its respective status (failure or suspension) and quantity:


With the life data analysis performed, the warranty forecast for the component was generated on the Forecast tab.


In the image above, the estimated forecast of returned items for the next six-month period is shown. If Round Values is selected, have in mind that the sum in the line “Total” will still be made considering all the decimal places in the cells above, so it may diverge from the sum of the rounded values shown in the cells when this option is selected (this was already pointed out in Chapter 6).


Forecast Plot:


The total amount of warranty returns for one year, based on the estimation is:

(0 + 2 + 8 + 10 + 21 + 30 + 70 + 115 + 176 + 256 + 358 + 482) = 1,528 units

Knowing that the costs related to this product include $20 of labor, $7.5 of raw materials and administrative cost of $15, the total budget for warranty returns is estimated to be:


(20 + 7.5 + 15) * 1,528 = $64,940.00

Reliability and probability density functions plots:


The probability of failure for the end of the warranty period:

Chapter 5: WA-NRI Case Studies
5.1 Case Study 1: Home Appliances Manufacturer
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