Molding process
- Pre-drying of pellets
| (1) | TOYOBO
NYLON is shipped as a dried pellet packed into a moisture-proof bag, then, if
the pellet is processed immediately after unsealing the bag, pre-drying of the
pellet is not required. | | (2) | However, If
the pellet is exposed in the air as it is, it will absorb moisture. Therefore,
please avoid exposing the pellet in the air for a long time. | | (3) | The
standard drying condition for moisture-absorbed pellets is set to 3 ~ 5 hours
at 80 ~ 120°C. However, please remember that drying for a long time
would cause coloring in the pellet due to oxidation. | - Setting
of cylinder temperatures
(Notes) Please set the applied temperature of purging resins not
more than 300°C for general nylons or 330°C for 6T-Nylon.
Otherwise, thermal decomposition occurs resulting deterioration in quality, which
will cause troubles with burning and poor hue. - About molds
(Particularly for reinforced nylons)
| (1) | Quality
of mold materials | In general, the reinforced nylons with fillers
such as glass fibers will develop larger mold abrasion during molding than use
of non-reinforced nylons. Therefore, please pay attention to the following. Especially
for the gate, please try to select a mold material in line with the following.
 | Alloy
tool steel such as SK, SKS or SKD treated with hardening and tempering may be
used as HRC55 ~ 60. |  | Pre-hardened
steel and precipitation hardening steel may be used. |  | Surface
hardening treatment is effective. - Rigid chrome plating treatment
- Nitriding
treatment
- Cermet treatment
| | | (2) | Gate |
When a gate is designed, it should be carefully considered for glass
fibers to avoid their snapping. As the fluidity of GF reinforced nylons is not
so good as non-reinforced nylons, it is important to give a well rounded corner
at the joint between a runner and a gate in order to reduce their flow resistance.
Since notable weld lines, reduced strength or deformations of moldings may
occur depending on the gate position, please give due considerations on them.
As a guide to the dimensions of a side gate, please take a thickness about 60%
of the molding thickness, a width as 1.5 ~ 3 times as wide as the gate thickness,
and a land length as about 50% of the gate thickness. For a pinpoint gate, the
gate size of 0.8 ~ 1.5É” will be an index. | | (3) | Vent |
| Reinforced nylons easily generate more gas than non-reinforced nylons
do. Thus, please ensure good breathing by fitting with air-vents of about 50 É m
deep in way of the region where resin flows meet. | Metal
quality and life
Estimating of life vs. mold hardness can be roughly guided
with the following chart. 
|
Processing