# Cg/Cgk - Special equipment that I'm not sure what to do

#### soulmas

##### Involved In Discussions
Dear all,

I need your help. I know how to calculate Cg/Cgk's however, I have a special equipment that I'm not sure what to do. After using the same reference part several times, the part gets damaged so, I cannot complete all the measurements required. What could you suggest?

My first guess is to have several reference parts (not just one...) and measure each part only for certain number (let's say 5 times each part) to avoid damage. Is this a good approach to this study? any idea?

thank you,

#### Wes Bucey

##### Prophet of Profit
Dear all,

I need your help. I know how to calculate Cg/Cgk's however, I have a special equipment that I'm not sure what to do. After using the same reference part several times, the part gets damaged so, I cannot complete all the measurements required. What could you suggest?

My first guess is to have several reference parts (not just one...) and measure each part only for certain number (let's say 5 times each part) to avoid damage. Is this a good approach to this study? any idea?

thank you,

#### soulmas

##### Involved In Discussions
Clarifying, the reference part is made by plastic. The equipment is a dynamometer, so the equipment apply effort on the part and the part gets bended. (20-40 N). After several times, the reference part is bended, and does not get back to the original form. or is torn or with scratches.

You are correct, the part gets damaged by the equipment. This is not a destructive test, but Customer is requesting Cgk for 50 measurements. I can probably consider this study as being "destructive" and this could be a special case where I cannot calculate Cg/Cgk. What do you think?

#### Wes Bucey

##### Prophet of Profit
Clarifying, the reference part is made by plastic. The equipment is a dynamometer, so the equipment apply effort on the part and the part gets bended. (20-40 N). After several times, the reference part is bended, and does not get back to the original form. or is torn or with scratches.

You are correct, the part gets damaged by the equipment. This is not a destructive test, but Customer is requesting Cgk for 50 measurements. I can probably consider this study as being "destructive" and this could be a special case where I cannot calculate Cg/Cgk. What do you think?
I think a frank conversation with the customer (the guy at the customer who has the final say) on a workable solution at a negotiated price is required. This is, indeed, a special case and requires special consideration AND PAYMENT for the time, effort, and materials involved.

Without seeing print and specs for both part and instrument, it's pretty difficult to suggest a quick and easy workaround.

Remember - modern quality practice suggests supplier and customer work as partners, not adversaries, for optimum results.

#### soulmas

##### Involved In Discussions
Thank you!! We...just like you say..we will work with the customer to find a solution on this particular case.. it will be handled as a special case.. first, we will run the study with 25 measurements only, to see when the part gets damaged. if we cannot complete 25 measurements, we will not conduct a Cgk study, but we will do a GR&R that will be our MSA study. Thank you for your comments.

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