beneath the pour spout. Depending on the operatingtemperature of the alloy being used, the die caster can presetthe Castool Cooling Jacket. A thermocouple then activatesa controller which increases or reduces the flow of coolantthrough the jacket as required.

Large diameter sleeves will always benefit from thermalcontrol. A series of gun drilled holes are positioned alongthe length of the shot sleeve under the pour spout, and areconnected to gun drilled holes around the die end ofthe sleeve. A thermal control unit is used to manage thetemperature and the flow rate of the medium (water or oil)to gain control of the shot sleeve temperatures.

Thermal Control Reduces WearFor maximum operating life, the plunger tip must movesmoothly through a round, straight shot sleeve, with a clear-ance of less than .004”. If the clearance becomes greater thanthis, the alloy can penetrate as flash or blow-by. This willimmediately cause excessive wear. The problem is to preventunequal thermal expansion which will distort the sleeve.

A typical shot sleeve may become 300ºF (150ºC) hotterat the bottom under the pour hole, than at the top in front ofthe hole. If the temperature of the sleeve is much higher atthe bottom than at the top, unequal expansion will cause it tobecome oval instead of round. Also, this will cause the sleeveto become slightly bowed instead of straight. Either of theseconditions will result in premature wear of both shot sleeveand plunger tip. To avoid this, the temperature at the bottomof the sleeve must be controlled so that the difference in tem-perature, bottom to top, does not exceed 120ºF (50ºC).

When is Temperature Control Necessary?For small diameter sleeves thermal distortion is usually sosmall that temperature control is seldom necessary. The flex-ible ring on the Castool plunger tip will conform to minorvariations in the bore.

Medium diameter sleeves may require thermal control.This can be determined by a temperature audit duringtypical operating conditions. Castool has an effective andeconomical cooling device which can be re-used when thesleeve is replaced. The Castool Pour End Cooling Jacketputs maximum shot sleeve cooling where it is needed most – (over)

Shot Sleeve System

Factors Affecting Amount of Thermal Distortion• Casting weight • Alloy temperature • Fill ratio• Cycle time• Thickness of sleeve wall • Length of sleeve• Size of pour hole

Shot Sleeve Design ParametersHigh shot sleeve temperatures usually result from short cycletimes, high filling ratios, and thin sleeve walls. The wallthickness should be at least 1/3 of the inside diameter of thesleeve. The size of the pour spout should be less than 70% ofthe bore of the sleeve. The unsupported portion of the sleeveshould be as short as possible to avoid bending.

Replaceable Wear BushingHigh temperatures and the velocity of aluminum impactingthe sleeve bore under the pour hole causes erosion. Castoolrecommends the use of replaceable wear bushings. Conicalmounting bolts force the split bushing to lock in place,providing good heat transfer. They can be easily replaced,even in the machine when necessary.

The Split CollarSteel prices have risen dramatically in the last few years.Castool recommends using a split collar that reduces thediameter of steel required to make most shot sleeves.The splitcollar may also allow the shot sleeve to be used in several diesby having multiple collars.

Castool Lubrication, Drop and SprayTo get maximum production from any cold chamber diecasting machine, effective lubrication of the plunger and shot

sleeve is absolutely essential. Insufficient lubrication willresult in inconsistent shot velocity, premature sleeve andplunger tip wear, and unnecessary scrap. Too much lubricantcan increase porosity. This will also produce costly scrap.

Castool has found it most effective to introduce liquidlubricant by an internal groove at the pour end of the shotsleeve. The lubricant is applied only where it is needed, thesurface of the ring or the leading edge of the plunger. Thisreduces the amount of lubricant used, and therefore reducescost significantly.

Long, large diameter sleeves require sufficient lubricantto coat the entire bore, especially at the die end wherepressure is the greatest. Best results are achieved by usingCastool’s Combi-Lube system. Lubricant is applied to thesurface of the ring and atomizing air and liquid lubrication issprayed into the sleeve bore.

Castool offers 2 liquid lubricants designed for thisapplication:

ALS192 is a liquid synthetic based boron nitridelubricant, designed for either aluminum or magnesiumcastings that will be welded, or for which good surfacequality is required.

ALS 196 is a mineral oil based lubricant developedspecifically for the Castool Lubrication System. Itmaintains an unusually low coefficient of friction at hightemperatures.

Benefits of Castool SystemWith the help of Castool to control the temperature of shotsleeves and plunger tips, and with proper lubrication, coldchamber die casters using the Castool Ring Tip Plungersystem are getting outstanding results... productivity and costsavings.

TEL 905.852.0121 FAX 905.852.2300 WATTS 800.268.42982 Parratt Road, Uxbridge Ontario Canada L9P 1R1sales@castool.com www.castool.com

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