By Justin Werth
Does your shop floor manager cringe at every announcement of revision changes or cor- rections to customer designs or drawings?
Do your engineers sit around for hours every week
writing new bills of material (BOMs) for those rev
changes? Do drawing and material list changes almost always translate into production delays that
lead to cost overruns and late deliveries?
CAD technology has revolutionized engineering
and design, but delays still can occur in manufacturing because of the document change process, which
in turn leads to cost overruns and missed due dates.
That document change process inevitably involves
making sure BOMs are current and correct. This can
be a lengthy, tedious task, especially considering
how large BOMs can get at certain companies.
Now, though, CAD so;ware can work with enterprise resource planning (ERP) so;ware. With the
two integrated, a fabricator can simplify the process
of building BOMs and improve their accuracy, and
the new data can transfer directly to the shop floor
via the ERP system. Establishing procedures and
adopting technology to ensure that smooth transition between CAD and the BOMs in the ERP system
can prevent a lot of headaches.
CAD Has Evolved
CAD programs make it quick and e;icient to update
drawings with other job-related documents. With
sophisticated 3-D modeling programs like Solid-
Works®, SolidEdge™, and AutoCAD®, engineers can
dramatically speed the process of creating the draw-
ings and designs required to manufacture complex
parts and products. If an engineer makes a change
to one component, the so;ware detects interfer-
ence and other design implications throughout the
rest of the assembly. For instance, if that engineer
changes the material thickness or the position of a
sheet metal component, the so; ware has the ability
to detect the fact that certain hardware pieces don’t
have enough threads to make a secure connection.
When those drawings need to be changed, CAD
programs can simultaneously update every view of
the drawings, thereby eliminating the time and expense of entering the data multiple times. However,
transmitting these updates from engineering to the
shop floor in a timely manner is where the delays,
errors, and additional costs typically occur.
First, all BOMs related to the job have to be manually updated by engineers to match the current version of the drawing being distributed to the floor.
Considering that engineering time is typically the
most expensive of all labor costs, this can add significant costs to a project. Additionally, new plans
need to be printed and distributed to everyone
working on the job.
Delays also can occur when engineers make data-entry mistakes while manually updating the BOMs.
If even one operator ends up working with an outdated version of the drawing, it can seriously delay
or even derail an entire project.
In companies that have a structured engineering
department (that is, more than one person), somebody creates the engineering change notification
(ECN). This can come from various places, depending on the manufacturer and its organizational
structure. It could come from production, if the
change would solve a production issue; it can come
from the head of operations in communication with
customer service, which received feedback or complaints from customers; or it could come from the
Once an ECN is initiated, people must follow a
structured process. Generally, it lands first in the
engineering department, then operations, purchasing, and costing personnel. Then engineering performs any further modification, then the final sign-o;. Once the sign-o; occurs, the production control
manager is notified.
If set up and integrated correctly, ERP systems
have helped implement these ECNs e;iciently by
sending notifications to the right people at the right
time, and asking for their input, review, or approval.
This creates a digital record and helps simplify the
ECN process compared to the old paper-based system, where ECN packets were passed around the
o;ice, spending hours or days in people’s inboxes.
The ECN procedure can vary depending on the
type of manufacturer, but digitizing the process can
help simplify matters immensely. Still, one manual
step remains: manually keying in information to update the BOM.
And mistakes can happen, particularly when the
fabricator has similar part numbers designating
entirely di;erent parts. In sheet metal fabrication,
for instance, part numbers reflect specific characteristics, like material grade or gauge. This means
that two di;erent parts can have similar (though of
course not identical) part numbers. One part may
be of 12-gauge material, while another may be 16
ga. One job may call for 6061 aluminum, while another may call for 6063 aluminum, and another may
be 5052. The chance for data-entry error abounds.
Then comes the issue of multilevel BOMs, which
amplify the problem. With a single-level BOM, the
fabricator makes one part, and every other component is purchased. Most fabricators manage multilevel BOMs, where the plant makes multiple parts
that come together into a larger assembly, which
can include parts made in-house as well as parts
from an outside source.
Another way to look at it: A multilevel BOM has
manufactured parts within a manufactured part.
A completed assembly can have many levels to its
BOM. It’s a bit like peeling back an onion. A final assembly has BOM levels associated with each subassembly, which in turn has BOM levels associated
with each weldment, which in turn has BOM levels
associated with each sheet metal part.
Better data management,
How integrating CAD and ERP drives improvement