REDUCE PRODUCTION COSTS
International competition during the last 15–20 years has made
MAINTAINING QUALITY, REDUCING PRODUCTION COSTS
more and more important also for the moulding of technical
rubber articles. As you know, great steps ahead have been made
to this end and by the state of the art involving moulding
techniques, presses, rubber compounds, tools and last but not
least… men in the plants.
The rubber waste disposal costs and “green” aspects are part of
Even if each practical case must be specifically evaluated cost-
benefitwise, all of them share one or more of these targets:
compound saving, productivity, faulty parts reduction, tool life.
How did the tool makers in love with their activity offer
innovative solutions to the above customer needs?
According to this perspective and respecting confidentiality I will try to
give simple voice to some artefacts implemented during such period by
an Italian tool maker. This company has 30 years experience, is
“connected” to the international “actors” of rubber moulding and is
equipped with presses for tool testing and research.
Thin film direct injection: its potential, customer requests to
cut down their production costs, the advent of new compounds
and some exercise with home made research tools made this tool
maker reconsider his own previous designs about this technique,
the result being that in some cases the dimensions of runners
and fans could be reduced by 15 to 20%.
The “cut off” tools automatically separate the moulded parts
from their runners, so reducing the rubber amount sent to the
cryogenic finishing equipment.
“Hook” injection, for selected applications, later, made it possible to
eliminate the third tool plate, so reducing the moulding sequence time.
… appeared on the market some time before for the one
nozzle presses, were redesigned by the tool maker in order to
control the compound amount to the exit nozzles (“drops”)
purge the system more easily
use them for any rubber compound, as better verified later.
The best conditions for compound waste reduction and productivity with
these systems are shown by the diagrams based on actual design data.
RU BBER CO MP O U N D
WAS TE ,
( % )
* 16 NOZZLE CRS MISSING
5 ,2 8 7 ,6 6 1 0 ,8 2 1 5 ,6 0 1 7 ,1 7 2 8 ,3 0
4 n o zzl e mo l d 52% 52% 52% 54% 54% 57%
1 n o zzl e mo l d 58% 57% 57% 57% 58% 58%
"O -Rin g" D I AMETER (1 . 7 8 CRO S S S ECTI O N )
CRS; conventional injection rubber waste comparison
For 320 O. Rings 0.36”x0.103“ compound saving and productivity are
improved by using a 16 drop cold runner system and a 23.6”x19.7” tool.
A big, heavy, annular seal is multiple point fed by the
CRS, so cutting down rubber waste and trapped air
Bi-component seals (50 and 80 S rubber) are automatically
moulded: the injection press has programmed sequences
for CRS and tool. High volume, top quality parts are
COLD RUNNER SYSTEM IN
INJECTION OF TWO COMPOUNDS
CRS TRAVELS OUT
TOOL CLOSES TO JOIN PARTS. TOOL OPENS.
MIDDLE PLATE MOVES AWAY
BI-COMPONENT SEAL DEMOULDING
Car, top engine, highly abrasive rubber–metal seals are moulded
using a 5+5 nozzle CRS and tool with plates hardened and machined
after. Best tool life and low compound waste achieved.
For the bellows these shaped tool plates make demoulding easier.
Heat treatment for tool cavities and inserts.
Expansion vessel (75”x18”x12”) injection fed by a cold
runner system. Automatic demoulding
The “TWIN DROP” (“BIUGELLO”) CRS introduced by the tool maker at the 2006
Duesseldorf “K” exhibition offers the best productivity and compound waste, so far. Two
51”x27“ tools for different heat exchanger seals are multiple point fed: same compound at
the same time. Stack tools can be used even if they are not ideal for top quality moulding
while the expensive magnetic platens can be justified in case of frequent tool changes.
Heat exchanger seals moulded with “Twin drop” CRS.
... Connected to the press and to the tool, to mould small-medium
size high quality articles.
The press choice is particulary important.
Automatic moulding of 126 caps sent to cryogenic finishing. Rubber
waste reduction, high productivity.
Injection cold transfer of seals considered
“flashless” for the occasion.
“NANO NOZZLE” injection transfer cold pot system delivering the
rubber compound-through tiny nozzles individually cooled down to
their tip-into the tool cavities or close to them. It was introduced by the
tool maker at Plast and, in operation, at the 2009 Nueremberg
International Rubber Conference, moulding there 44 diameter shaped
membranes 0.9” diameter with 5. 50% rubber waste!
Nano nozzle injection point
... first developed in US, to mould flashless high volume articles and
expensive compounds (provided a small injection cone is acceptable).
Each tool cavity only receives the rubbers amount to fill it.
The Italian tool maker I am refering to is testing its CRS coupled to
the gating valve system - electronics supplied by an experienced
company, aiming to use any compound; any one nozzle press of
suitable capacity; any valve rubber feed sequence. No calibration
needed for different thickness tools.
…whenever applicable, the automatic
demoulding of such parts as shock
absorbers, seals, etc. and the tool hard
chrome plating jointly reduce the rate of
damaged parts and the total moulding cycle
Robot loading metals on the tools has
been used for high volume metal-rubber
…“in house” trial moulding of complex tools using
customer’s compound, prior to tool despatch, might avoid
production delays, later.
… hard chrome plating is
moderately priced and
normally it favours the
rubber compound flow,
reduces the chemical attack of
most compounds; keeps tool
cleaner and remarkably
extends the tool useful life.
…hardening tool plates, followed by machining is appreciated in
case of gritty compounds. Such procedure, in absence of undercuts, can
replace tool inserts (if prescribed) to the advantage of tool productivity.
Any production demaged hardened insert, say of a 3000 insert
pharmaceutical industry tool, can be replaced regardless its position in
the tool. Only highly qualified tool makers make this possible.
Experience has demostrated that new, complex mulding techniques and
sophisticated equipment are rarely in the interest of a moulding company
with inadeguate experience.
Menare a main moulding company asset also concerning PRODUCTION
As you know, successful moulding
companies must constantly watch and
look into innovation. Sometimes the
compound and equipment suppliers
have played useful collaboration roles
about that, for instance, in the so called
“turn key jobs”.
Many thanks for your patience. Any questions?