Inverted Delta - What does an inverted delta on a print represent?

R

randymhl

#1
Hello Everyone,
What does an inverted delta on print represent?
 
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Stijloor

Staff member
Super Moderator
#3
Re: Inverted delta

Hello Everyone,
What does an inverted delta on print represent?
Hello Randy,

I have to guess on the origin of the print you're referring to. An inverted delta on a print (possibly from Ford Motor Company and associated organizations) means that this signifies a special characteristic.

From Ford:

Inverted Delta parts
For parts designated as inverted delta (parts with Critical Characteristics), the organization shall prevent the shipment of non-conforming product to Ford.
Note: this is typically accomplished by using error and/or mistake proofing techniques integrated into the organization's manufacturing and material handling processes.


Look here (.pdf file) for more information.

Hope this helps.

Stijloor.
 

Jim Wynne

Staff member
Admin
#4
Re: Inverted delta

Welcome Randy, even though I realised you were a user even before me.

If I am not mistaken, you are referring to 'rho' - Wikipedia reference-linkRho_(letter).
This is the Greek letter delta: Δ
Turn it upside-down and you have an inverted delta. What it means in terms of engineering drawings differs greatly. As Stijloor has already pointed out, Ford uses it to denote special characteristics. If you're not dealing with Ford drawings, you need to ask the customer because there's no telling what it might mean. Note that many companies use delta right-side-up to flag revised specifications on drawings.
 

Miner

Forum Moderator
Staff member
Admin
#5
Re: Inverted delta

I have to guess on the origin of the print you're referring to. An inverted delta on a print (possibly from Ford Motor Company and associated organizations) means that this signifies a special characteristic.

From Ford:

Inverted Delta parts
For parts designated as inverted delta (parts with Critical Characteristics), the organization shall prevent the shipment of non-conforming product to Ford.
Note: this is typically accomplished by using error and/or mistake proofing techniques integrated into the organization's manufacturing and material handling processes.

Look here (.pdf file) for more information.
If the drawing is a Ford drawing the inverted delta means more than a special characteristic. It means a critical characteristic, which means a safety characteristic typically involving compliance to Federal Motor Vehicle Safety Standards (FMVSS).
 

Stijloor

Staff member
Super Moderator
#6
Re: Inverted delta

If the drawing is a Ford drawing the inverted delta means more than a special characteristic. It means a critical characteristic, which means a safety characteristic typically involving compliance to Federal Motor Vehicle Safety Standards (FMVSS).
Let me remove all doubt:

From Ford CSR's:

Ford Designated Special Characteristics
Critical Characteristic ( ∇ ) Parts
Ford designated Control Item Parts are selected products identified by Ford Engineering, concurred by Ford manufacturing and identified on drawings and specifications with an inverted delta ( ∇ ) preceding the part and/or material number. Control Item products have Critical Characteristics (refer to the Glossary of this document) that may affect safe vehicle operation and/or compliance with government regulations. Unique symbols identifying safety and regulatory characteristics on components designed by other companies (e.g. Mazda) are equivalent to the inverted delta ( ∇ ) symbol. Examples are the Mazda "A" and "AR" symbols or special fastener base part numbers beginning with "W9" which are to be treated as inverted delta. Critical Characteristics for fasteners may be designated by methods defined in Ford Engineering Fastener Specifications available through Ford Global Materials and Fastener Standards, or the specification providers listed in 4.2 of this document. Other Special Characteristics Significant, High Impact and Pass Through Characteristics are described in the glossary of this document.


Stijloor.
 
D

David DeLong

#7
All inverted deltas on Ford drawings should have statistical control of some sort starting with capability studies with a Ppk of at least 1.67 and long term controls such as an X bar and R chart.

Make sure that in your Control Plan you place the inverted delta in the column for significant characteristic on the specific characteristic that was shown on the Ford drawing.

Hope this helps.
 

Marc

Hunkered Down for the Duration with a Mask on...
Staff member
Admin
#8
This is kinda dated, but may be helpful in putting thkngs into perspective with respect o how every company defines their print contents, to some degree, differently: Print Characteristics.
 
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