THE
V-PROCESS
THE
V-PROCESS
WHERE IT STARTED
The V-PROCESS (technically vacuum molding) was developed and patented in Japan in the late 1970's. Bill
Wilmont, President of the Herman Molding Machine Company in Zelienople, Pennsylvania, was
instrumental in bringing the process to the United States. Wilmont quickly saw the value of the process and
left his position to open Harmony Castings, Inc. in 1981.
Because of the recession in 1981, Harmony Castings experienced financial difficulties from the start. In
addition, there was virtually no technical expertise available in the United States. Despite these conditions
and with perseverance and a belief in the value of the process, the Company was able to quickly establish a
market. In 1986, Harmony was sold to the present management and a strong emphasis was placed on
upgrading the quality of the castings produced. At that time, the Company had 11 hourly employees. In the
succeeding 12 years, Harmony has grown to approximately 130 employees, with sales of more than $15
million projected for 2000. In July, 1999, Ligon Industries purchased Harmony Castings and within a couple
of years Ligon Industries purchased TPi.
The process has been used and accepted by companies ranging from Fortune 100 to start-ups and is proving
to be a very cost effective process for producing tight tolerance, esthetically pleasing, thin wall aluminum
castings. The value of the process has enabled many companies to minimize the cost of new designs and to
reduce the cost of current programs.
Major markets are in the medical, instrumentation, electronics, computer and tele-communication. We excel
at long term projects requiring accurate, high quality castings.
Harmony Castings and TPI continue to challenge the process, people, and systems to produce a product that
exceeds market and design expectations. Quality has been the vehicle for growth and V-PROCESS will
continue to satisfy the designs
ZERO DRAFT
The
V-PROCESS
is unique in that
it
DOES NOT REQUIRE ANY DRAFT ANGLE
.
This is due to
the lubricity of the plastic film that allows for the mold to be stripped from the pattern without the
friction of the sand against the pattern. The vacuum that is applied during the film forming operation is
released and the vacuum is then applied to the mold. This causes a slight, controlled expansion or
contraction of the mold features. The advantages of the zero draft capabilities are:
Constant Wall Thickness
for weight reductions and aesthetic appeal.
Elimination of Machining
off the draft for clearances for mating parts.
Total Tolerance
range remains for the actual feature, not the feature plus draft. Draft does not
use up the tolerance.
Pattern Construction
is more accurate and efficient.
For more information or a competitive quote please contact:
TOM CLARK
McCann Sales, Inc. Ph: 207-439-3747
: tclark@maine.rr.com
HOW IT WORKS
First, we heat a thin plastic film and place it over a pattern. A vacuum tightly draws the film over the pattern,
which is then surrounded by a flask. Next, we fill the flask with dry, unbonded, extremely fine sand and
vibrate the sand so that it tightly packs the pattern. After a second sheet of film is placed on the flask, a
vacuum draws out the air, and the completed mold is then stripped from the pattern.
Each half of the mold is made in a similar fashion and then aluminum is poured directly from the furnace
into the closed halves. The mold is held under vacuum to retain its shape. After the mold cools, the vacuum
is released and the sand and completed castings fall free.
Simple in concept and far reaching in impact, V-PROCESS produces quick turn-around, high-value castings.
In order to provide the highest quality product, Harmony Castings continually strives to improve our systems
and raise the level of our performance. To achieve these standards, we maintain ongoing training programs
that teach our employees to accept responsibility and to act on their knowledge. The caliber of our people
and the quality of our V-PROCESS make it possible for Harmony Castings and TPi create a vision for the
future, and to establish our Company as a leader in the casting industry.
It is no accident that major companies in the medical, instrumentation, electronics, computer and tele-
communication industries rely on the V-PROCESS for their casting needs.
MOLD SIZES
Between Harmony Castings and TPi they have the following basic mold sizes:
36” x 36” x 12” / 12” ( 24 inch total height )
36” x 48” x 14” / 12” ( 26 inch total height )
As a rule of thumb, we need a minimum of 2 – 5 inches in the length and width for the gating system
depending on the shape and size of the part. When in doubt, do not assume a part will fit. Send us the
drawing for evaluation.
CORING
The V-PROCESS uses cores that are similar to a sand core with the exception that we coat the core with
a ceramic wash. The purpose of this is to seal the coarser core sand so when a vacuum is pulled on the
core the aluminum is not sucked into the core resulting in a “burn in” condition.
For more information or a competitive quote please contact:
TOM CLARK
McCann Sales, Inc. Ph: 207-439-3747
: tclark@maine.rr.com
V – PROCESS BENEFITS
Very Smooth Surface Finish
•
125-150 RMS is the norm. Cast surface of 200 or better, based on
The
Aluminum Association of America STD AA-C5-E18
.
Excellent Dimensional Accuracy
•
Typically +/-.010 up to 1 inch plus +/-.002 per additional inch. Certain
details can be held closer.
•
+/-.010 across the parting line.
•
Cored areas may require additional tolerances.
Zero Draft
•
Eliminates the need for machining off draft to provide clearance for
mating parts and assembly.
•
Provides consistent wall thickness for weight reduction and aesthetic
appeal.
•
Allows for simple fixturing for machining and inspection.
•
Pattern construction becomes more accurate and efficient.
•
Total tolerance range becomes more accurate and efficient.
•
Geometry/tolerance of part is at its simplest form. Draft does not use
up tolerance.
•
Design/drafting is less complex. Calculations and depictions related to
draft are eliminated.
For more information or a competitive quote please contact:
TOM CLARK
McCann Sales, Inc. Ph: 207-439-3747
: tclark@maine.rr.com
V – PROCESS BENEFITS CONT.
Thin Wall Sections
•
Walls as low as .090 in some applications are possible.
Excellent Reproduction Of Details
•
Very small features and lettering are possible.
Consistent Quality
•
All molding is semi-automatic. Variable "human factor" has been
reduced.
Superior Machining
•
Sound metal and no hidden sand in the castings means fewer setups,
reduced scrap and longer tool life.
Low Tooling Costs
•
All patterns are made from epoxy, machined plastics, SLA or LDM.
There is no need to retool for production quantities.
Unlimited Pattern Life
•
Patterns are protected by plastic film during each sand molding cycle.
For more information or a competitive quote please contact:
TOM CLARK
McCann Sales, Inc. Ph: 207-439-3747
: tclark@maine.rr.com
V – PROCESS BENEFITS CONT.
Easy Revisions To Patterns
•
No metal tooling to weld or mill. Great for prototypes.
Short-Run Production Capability
•
Excellent for short-run production while waiting for hard tooling. The
V-PROCESS method can out produce traditional prototype methods
such as plaster or investment castings.
Fast Turnaround
•
From placement of order to sample casting in as little as two to four
weeks
For more information or a competitive quote please contact:
TOM CLARK
McCann Sales, Inc. Ph: 207-439-3747
THE VACUUM PROCESS
The pattern ( with vent holes ) is placed on a hollow carrier plate.
A heater softens the .003” to .008” plastic film. Plastic has good elasticity and a high deformation ratio.
Softened film drapes over the pattern with 200 to 400 mm Hg vacuum acting through the pattern vents to
draw it tightly around the pattern.
For more information or a competitive quote please contact:
TOM CLARK
McCann Sales, Inc. Ph: 207-439-3747
E-mail:
THE VACUUM PROCESS CONT.
The flask is placed on the film-coated pattern. Flask walls are also a vacuum chamber with the outlet shown
at right.
t vib
The flask is filled with dry, unbonded sand. A sligh
ration compacts sand to maximum bulk density.
. The
A sprue cup is formed and the mold surface leveled
back of the mold is covered with unheated plastic
film.
For more inform
act:
McC
747
: tclark@maine.rr.com
ation
te please cont
TOM CLARK
or a competitive quo
ann Sales, Inc. Ph: 207-439-3
THE VACUUM PROCESS CONT
.
ed to the flask. Atmospheric press re then hardens the sand. The vacu
Vacuum is appli
um is released,
pressurized air is introduced into t
old is stripped.
u
he carrier and the m
The cope and drag assembly form a plastic-lined cavity. During pouring, molds are kept under vacuum.
d and free-flowing sand drops away le
After cooling, the vacuum is release
aving a clean casting, with no sand
lumps. The sand is cooled for re-use.
For more inform
act:
McC
747
: tclark@maine.rr.com
ation
te please cont
TOM CLARK
or a competitive quo
ann Sales, Inc. Ph: 207-439-3
FREQUENTLY ASKED QUESTIONS
What does the "V" stand for in V-Process?
The "V" stands for vacuum. The mold is held together under a vacuum.
Why don't you need draft with this process?
B
initial sheet of plastic film
old, the mold will "pop"
enough to facilitate the removal of the pattern.
When should you use the V-Process?
W
pi
e
permanent
ances and
repeatability over a sand casting, then the V-Process also makes sense.
I need a short run of castings very fast. Can the V-Process accommodate me?
communications, company
d flow. We also use rapid
prototyping tooling technology in our pattern process.
For more information
te please contact:
McC
747
:
tclark@maine.rr.com
ecause the plastic provides for less friction on the pattern than a direct sand contact. Furthermore,
this plastic barrier provides for unlimited pattern life. Also, when the vacuum that is holding the
down is removed and applied instead to the m
e recommend the V-Process for prototyping and low to medium volume casting work (up to 15,000
eces per year). It is a very suitable alternative to plaster or investment casting and lower volum
mold or die-casting. If you are looking for improved surface finish, toler
Yes. We specialize in rapid prototyping. This involves much more than making one order fast. It requires
culture and linked facilities that schedule parts for rapi
or a competitive quo
TOM CLARK
ann Sales, Inc. Ph: 207-439-3
V-PROCESS CASTING
Heater
Pattern
Vacuum Chamber
Plastic Film
Cope
Drag
Mold Cavity
Sprue / Runner
Parting Line
1.
e mold to the gating and riser system. Also, a generic
3.
a mold produced by the removal of the pattern. When filled
6.
G LINE
:
A line on a pattern or casting corresponding to the separation between the parts of
7.
or machined plastics around which molding
9.
ILM
:
Ranging from .003” to .008” it is used to stretch to form over and into features of
10.
VACUUM CHAMBER
:
When a vacuum is applied to it, it draws the plastic film over the pattern.
For more information
te please contact:
McC
747
: tclark@maine.rr.com
DEFINITIONS
SPRUE
:
The vertical channel from the top of th
term used to cover all gates, runners and risers.
2.
RUNNER
:
The portion of the gate assembly that connects the sprue to the casting in gate or riser.
MOLD CAVITY
:
The impression in
with molten metal it forms a casting.
4.
COPE
:
Upper or top most section of a flask, mold or pattern.
5.
DRAG
:
Lower or bottom section of a flask, mold or pattern.
PARTIN
a mold.
PATTERN
:
A pattern made from wood, metal, epoxy
material is placed to make a mold for casting metals.
8.
HEATER
:
Used to soften the plastic film before it is drawn around the pattern.
PLASTIC F
the pattern.
or a competitive quo
TOM CLARK
ann Sales, Inc. Ph: 207-439-3
MECHANICAL PROPERTY LIMITS FOR COMMONLY USED
SAND CASTING ALLOYS
Alloy
Temper
Ultimate ( ksi)
Yield (ksi)
% Elongation
Hardness
1000 PSI
.2% offset
Brinell
356
F
19
- -
2
40 - 70
356
T51
23
16
- -
45 - 75
356
T6
30
20
3
55 - 90
A356
T6
34
24
3.5
70 - 105
319
F
23
13
1.5
55 - 85
319
T5
25
- -
- -
65 - 95
319
T6
31
20
1.5
65 - 95
535
T5
35
18
9
60 - 90
Note: The above properties are believed to be correct, but are not warranted in any way by McCann Sales, Inc. “F” as cast condition
GENERAL DESIGN DATA
SIZE RANGE
: Up to 150 lbs.
METALS
:
Aluminum Alloys 356, 319, 535,735
TOLERANCES
:
+/- .010” for 1” then add +/- .002 inches/inch
PARTING LINE SHIFT
: +/- .020”
AVERAGE TOOLING COST
: $ 3,000 to $ 9,000
TYPICAL ORDER QUANTITY
: All
AVERAGE TOOLING LEADTIME
: 2 to 4 weeks
SURFACE FINISH
: 125 to 150 RMS
MINIMUM SECTION THICKNESS
: .090 “ premium / .125” average
MINIMUM DRAFT REQUIRED
: Zero
Note: The above information is meant to be a basic guideline for comparison purposes only.
For more information or a competitive quote please contact:
TOM CLARK
McCann Sales, Inc. Ph: 207-439-3747
: