Dear All

We are OEM supplier to all tractor companies. We have 15 different type of axles and other 20 components.

3 stages of process- Input is turned blank components

• Hobbing ( spline) first stage process
• Induction Hardening
• Grinding

Then final inspection and dispatch.

How to calculate SIGMA LEVEL of unit.

please advice

regards

Manu

Dear Manu,

Although many people like to calculate Sigma Level for a company, I feel it is futile exercise. Let me explain why I think so.

• Sigma level calculation requires that we ensure collection of reliable data for the process of interest. Ensuring reliable data for all processes in a company shall be a huge cost and may not serve a business purpose.
  

• Even if we assume that assessment of sigma level for critical processes can be used to compile sigma level for the company, we must remember that sigma level is a dynamic measure. Sigma level for a process can change the moment customer (internal or external) exception changes or if the defect definition changes. This means, whenever you announce a specific sigma level for your company, the validity of the announcement may be questionable as customer expectations for some processes might have changed.
  

• In my opionion, it is best to use Sigma level assessment for current situation and improved situation on a project by project basis.
  

Comments on the subject are welcome.

Warm Regards,

Vikram

Dear Mr.Vikram kanna,

 Can u pl explaing more specifically how to calculate sigma level of an organisation.

 

thanks

JK

 

Hi,

I welcome Vikram's view on companywide Six Sigma Calculations & would like to share my opinion on one of the points raised.

No doubt, in today's competitive world, customer requirements are really squeezing at a brisk pace, which is a great challege for all the industries especially the Service Industry.

Basis the capabilty of our Critical Processes, no doubt we can figure our company's Six Sigma Level, but it should be supported by a protocol, wherein the dynamics of changing customer requirements are taken care of.

Moreover, one needs to study the way few Six Sigma pioneer Industries have projected themselves on the highs of Sigma Level i.e. MOTOROLA, Wipro etc.

Your feedbacks are welcome.

Regards,

Naveen Pilania

 

 

Dear friends , i would like to through light on the subject of sigma level calculations at orgnization or unit level.

Please follow the following steps.

1. Identify the Business CTQs. i take example of a manufacturing unit. The four critical Business CTQs are Productivity, Cost, Quality and Customer complaints.

2. Decide KPIs for these KRAs and UoM . Like

Productivity - Ton per day or Kg /hour etc ( Treat variable data)

Cost - Rs / ton or Rs /Kg (treat variable data)

Quality - Defective ubits vs total units produced in the period for which

sigma level is being calculated (treat attribute data)

Customer complaint - Total units supplied vs unist with complaints

Use the scroll up sigma level template to calculate combined sigma level of all 04 parameters to get the UNIT level sigma level.

This can be done on monthly , quarterly or yearlly basis or for any period.

I do not see any problem with changing specifications bcos it will be taken care by defect defintions iself.

If you need any more inputs on this topic then feel free to contact me here.

I have enough experience to deal with sigma level calculations and i think i can try to calculate sigma level of any function, unit, organization.

Regards

sanjay

MBB-Mumbai

Sigma level is defined in terms of the ratio of the customer specs to the standard deviation.

Thus it is a relative measure of the variation in process in comparision to the customer requirement.

In that sense, it is not right to talk about the Sigma Level of the company. Even if we do, we will actually be talking about the Sigma level of the product characteristic in comparision to the customer expectation.

So, in your case also you have to define the crtical customer specific characteristic of your product and then evaluate its variation in relation to the range specified by the customer to evaluation your sigma level.

I agree with Vikram Khanna. It is futile to talk about the sigma level of the "company" on the whole. There are too many variables - not all are necessarily measured, nor that all are specified. It is futile and inefficient even if tried....

 

One way of defining the Six Sigma level is by translating the rejection levels into sigma level.

For example saying 3.4 ppm is a six sigma (short-term) level.

Even in this case, we will be talking only about a final product and not the whole process of the company.

If we talk about the whole company, we need to talk about the variations and wastages at all stages... and there is no way you can combine all into one sigma level number - since not all processes may be sequential or related in a static way.

So, I do not support the view of defining a single sigma level for an organization as a whole.

 

Hello Manu:

I could understand that you are actually finishing a turned part(should be a forged shaft - CK45(must be a medium carbon steel material)).

If the spline is hobbed then it should be stub tooth.

Then you would be induction hardening the same on the splines,shaft(wherever needed) and then you would be grinding the induction hardened area(except splines)

(grinding tolerance should be ranging from 0.022 mm ~ 0.1 mm)

After this, i suppose you would be doing a magnetic particle examination for determining the quench cracks.

Here's my take on the matter.

You should first establish the process by

a) conducting a machine capability study (Cm,Cmk)

establish the process potential - Pp and Ppk

c) Conduct an on-going process capability study (Cp,Cpk)

If your cp,cpk is less than 1.67 and more than 1.33 then you would at 3sigma level with 99.73%

This is the starting point and you should continue to improve your process in each stage to achieve a Cp,Cpk more than 2.00

It is generally tough because of the inherant variability associated with the material,machine etc.,

3 sigma should be the ideal.

Hope this should give you some insight.

If you need any further info,please revert.

Thanks for the article.. Now I know how to calculate six sigma levels of any company..