|
PRODUCT
DESIGN FOR WELDABILITY
By
Doug Longenecker
The
product design phase of an arc welded commodity is extremely
crucial in developing a weldable product.
We at DPLongenecker L.L.C. are frequently contacted to
evaluate a welding line that is experiencing weld quality
problems that are directly related to product design issues.
Design for weldability is a necessity in planning for
success with an arc welded system.
Below are some key product design fundamentals for
product weldability:
1.
Design of Linear Weld Joints Preferred
2.
Compromise of Torch Angles Not Allowed
- An
allowable “window” for torch angles must be developed
before the product design phase of a program.
The product engineer must understand that a
compromise of torch angles will jeopardize weld integrity.
One suggestion is to submit a 3-dimensional model of
the proposed welding torch with the required torch angles to
the product designer.
3.
Welding on Radii or Hard Corners not Preferred
- Welding
on a hard corner or on a radius increases the potential for
a burn through condition.
Maintaining proper electrode stick-out and torch
angles becomes very difficult.
All arc starts and arc ends should maintain a 5 mm
distance from radii or hard corners.
4.
Minimization of Weld Length
- This
one may seem like common sense, but we often see this
concern not addressed during the product design phase. One way to address this issue is to conduct durability
testing on a prototype assembly with a reduced overall weld
length. Decreasing
weld length increases the probability of producing quality
welds, and also decreases consumable costs at the same time.
5.
Detail Part Dimensional Tolerances
- DPLongenecker
L.L.C. recommends that any weld flange must be able to meet
a profile of surface tolerance of + .5 mm.
Secondary trimming operations are typically required
to meet this requirement. Flange tolerance is directly related to the proposed
electrode diameter. The
larger the wire diameter, the greater allowable flange
tolerance for weldability.
Make certain to reference your customer’s arc
welding specification for maximum allowable gapping.
6.
Clamping and Welding
- Holding
a weldment in a fixture or “clamping” during welding is
also very important in most cases to insure quality welds.
This technique will greatly reduce the chance of gaps
in parts due to thermal distortion caused by the welding
process. Proper
weld schedule sequencing is very important as well to keep
distortion to a minimum.
When designing
the weldments, even before testing, take these things into
consideration. Many times, products are designed without
taking into consideration the joining process, even when a lot
of the issues could be taken care of prior to testing.
For
any further questions regarding design for weldability contact
Doug Longenecker @ 248-563-8625 or longeneckerd@aol.com
|
