Thermal Pin Design Guide

Design Guide

The following guidelines are designed to point you in the right direction for using THERMAL PIN heat conductors (TPhc), but they are only guidelines. Changes in one variable can be used to offset problems you encounter meeting the specifications in the guidelines. Please call our sales engineers if you have any questions.

MAXIMIZE HEAT INPUT AND OUTPUT

Choose the largest diameter TPhc possible without weakening the core. Also "A" should be 1/4" in diameter larger than the TPhc for good turbulent flow.

Order a TPhc long enough to extend well into the coolant channel. Leave approximately 1/8" at "B"

Optimally, D≤4C. If you think your application may be marginal, call to discuss your application with a sales engineer to see if TPhc's will benefit you.

The TPhc should be installed as far into the core as possible. Keep distance "E" as short as possible while maintaining the structural integrity of the core (it's safe to drill within assembly clearance of the tip of the core because TPhc's cause no corrosion or thermal shock to weaken the core).

COOL SMALL CORES

If you're cooling a small core, you should consider using a stepped TPhc to allow maximum heat output through the water channel. The larger o.d. should be less than two times the smaller o.d.

Another way to cool a small core is to make a THERMAL PIN core. Rather than installing a TPhc into the core, we fill the core itself. The extension cap provides maximum heat transfer to the water channel. Where possible, you should install TPhc's rather than have the cores filled. TPhc's cost less and installation generally takes less time.

Operate TPhc's in a horizontal orientation or tilted with the heat input at the bottom

TPhc's are usually installed so that they will operate in a position which is parallel to the floor, as is typical in injection molding. The TPhc's heat carrying capacity can be increased by as much as 360% by situating it in a vertical position with the heat input at the bottom. Conversely, heat introduced at the upward end reduces the TPhc effectiveness. The extent of that reduction depends on the distance that the heat must travel downward. The distance should be 6 inches or less. When ordering for this orientation specify type "Positive Lift." TIP: You can get extra performance out of your TPhc's by tipping the core so that the heat output end is higher than the input.

COOL THE TPhc with WARM COOLANT.

TPhc's work best when the coolant is between 60°F and 110°F and often higher. (Die casters can set the temperature of the coolant as high as 190°F.) For best results, start with the temperature high and then work down. See the graph below. Call our sales office if you need to run chilled coolant.

Determine and specify a TPhc to the final size and configuration. Do not machine, cut or bend TPhc's or cores after TPhc's have been installed.

Noren Products can supply you with the size you need (including metric and undersized) and the shape you want, e.g., baffled or finned. You should also be aware that you cannot mold onto TPhc's or apply force against them. If you need to rework your cores, we can advise you about the necessary procedures.

Order the right temperature range.

The maximum "operating temperatures" of standard TPhc's are 400°F and 600°F. Operating temperature: is dependent on the following temperature: injection, melt, mold surface and coolant. The TPhc can therefore be exposed to temperatures higher than the maximum operating temperature. If the TPhc overheats, it releases a small amount of non-toxic gas and becomes inoperative.

The 400°F TPhc covers the temperature range for most plastic processing. Die casting requires 600°F TPhc. Please call if you have an application for a THERMAL PIN heat conductor designed for higher temperatures.