Linotype Company Hot Metal Thermex Mold Disk –
water cooled — 15 lines per minute

Now THERMEX gives you all of these advantages:

        • Continuous high-speed slug casting on one mold
           • Faster wide-measure casting of display sizes
           • Cooler operation for solid slugs ... less matrix damage
           • New back knife for perfect type-high
           • Higher mouthpiece temperature aids type face quality

The Thermex is a newly designed water  cooled Linotype mold disk which greatly enhances efficiency and quality in high speed linecasting.

With the Thermex, slugs can be cast continuously on one mold at the fastest matrix assembly rates-even on a tape operated Elektron. The Thermex offers full 4 magazine versatility with a 4 mold disk. No more mold alternation for cooling.

Even with display sizes the potential speed of tape operated composition can now be realized.

The cooler operation of the Thermex helps protect matrices from possible type metal accumulations which could produce damage under vice jaw pressures. The precise adjustment of mold temperature to the requirements of each type of work ensures high typeface quality.

Elektron Introduced in 1964

The Thermex mold disk was developed later – 1966

Production claimed by Mergenthaler for output was  continuous casting on same mold  at 14 lines per minute.

Nobody believe it then,

but it accomplished the feat!

Not for just 5 minutes.

We had many runs for 1 hour or more.

Wisconsin Cuneo Press, Milwaukee, Wi. owned two ACE –  Automatically Controlled Elektrons.

Quite a challenge. Never a dull moment. Mold cooling hoses intertwined with hydraulic hoses which wound thru wires that kept communication going between 100 or more micro switches, leaf contacts, relays, servo motors, electric clutches, pumps and one matrix detector light beam. Mold turning and knife block servos received instructions for settings from a bank of relays located inside a cabinet about the size of a 1940 refrigerator. (55” high x 24” wide x 24” deep) All commands came from TTS punched paper tape via leaf switches located under the Teletypesetter Operating Unit.

— j merrill - head machinist


The widespread use of tape operated Linotypes and the popularity of the new  Auto Controlled Elektron have created a need for increased mold disk heat dissipation, to permit full utilization of the higher matrix assembly rates, In response to the new requirements, Mergenthaler Linotype Company has developed the Thermex mold disk.

But the importance of the Thermex goes beyond its application to tape-operated equipment. Both the efficiency and operational convenience of practically all Linotypes now in use can be greatly improved with the Thermex.

Large display type can be cast continuously on one mold, even at the speed of the new Auto-Controlled Elektron. The slug is always solidified completely before the mold is moved away from the pot mouthpiece; this insures slug homogeneity and maintains the correct shrinkage patterns for which the matrices have been designed. Cooler operation also prevents adhesion of type metal to matrices and spacebands, thereby reducing damage to matrix edges from type metal accumulations. Improved mold temperature uniformity maintains typeface quality.


In addition to its unmatched slug casting efficiency, the Thermex offers another great composing room bonus -significant reduction of type makeready time.

The allnew "floating" back knife trims the slug flush with the back of the mold, maintaining uniform type-high.

Although maintenance of type-high is not related to heat dissipation, other engineering problems encountered in the development of the Thermex disk led to a study of the mechanical factors responsible for type-high variation.

These factors have now been overcome in the Thermex through a complete redesign of the back knife mounting arrangement.


With the Thermex disk, type-high variation is reduced to the vanishing point by trimming the slug flush with the face of the mold. This has been accomplished by springloading the back knife fixture. Solid contact is maintained between the blade and the mold face, with ample pressure to insure precise flush trimming, without danger of abrasion and wear on the mold face.

As the disk revolves from casting to ejection positions, a system of mechanical linkages to a cam on the main drive shaft raises and lowers the knife assembly. The blade is therefore protected from damage, since it is brought into contact with the mold face only when the mold is in the trimming position.

The new spring-loaded back knife eliminates meticulous manual adjustment of knife-blade clearance. In addition, type-high variations requiring correction through time-consuming insertion and manipulation of equalizing shims, are significantly reduced.


Sensitive water-flow control is provided through a precise regulatory system. This system consists of a water flow adjustment screw and gauge, and an automatic valve which prevents excessive cooling by stopping water flow during the ejection cycle. A switch is provided to permit continuous water flow when needed for display point sizes.

Guided by actual equipment performance under the particular environmental conditions prevailing in his plant, the Linotype operator determines the best water flow rate for each kind of work and marks the corresponding float level on the glass tube indicator of the flow gauge. Thus after a brief period of use experience, mold temperature can be accurately set for all types of work.

The start/stop water valve located above controlled the cold water flow thru the top and bottom cooling bars (see below) clamped onto the molds. When the ACE Elektron received a stop code (a micro switch didn’t get activated at proper time) due to a machine malfunction, the timer and memory system would issue a stop command to the main drive clutch brake, the water flow valve, and issue hold to the stop magnets on the TTS (Teletypesetter Operating Unit) which would stop selecting anymore matrices or mats for assembly,


Where water supply is limited, the Thermex disk may be operated with a re-circulating water cooling unit.

Moreover, this arrangement is advantageous in all installations, since it offers thermostatically controlled water temperature. It also allows the use of distilled or de-mineralized water to insure trouble-free water circulation.


Special molds are required for use with the Thermex Mold Disk.

On a Thermex disk, the upper mold clamp is in the form of a straight, square metal bar instead of the curved shape found in conventional disks. This makes it possible to pass the tubing directly through the clamp, while allowing a tubing configuration inside the disk that will tolerate the necessary radial movement of the clamp. Redesigned molds, with accessory filler bars to reduce tube flexure in clamping molds of varying point sizes are therefore required. The Thermex molds are also specially designed to produce standard .918" type-high slugs in conjunction with the flush trimming back knife. The mold complement for the Thermex disk has been worked out to meet all significant current slug configuration and point size demand as efficiently as possible.


The Flush Trimming Back Knife!
A ninth wonder of the world!

It actually moved up (by cam/roller lever) to the back of the mold (actually rubbed on the steel mold) as the slug and mold were rotated by the mold disk back to the eject position. At the proper moment when the other end of the mold reached the back knife the cam/roller allowed the back knife to move back, with help from a back knife return spring) to normal resting position on the mold adjusting screw. Adjustment between resting knife edge and back of mold was .010``. The sharp edge had a special angle ground on it. (Sylben Engeering, Braidwood, Illinois) created this feature for Henry Cieko, Area Mgr. for Mergenthaler, 531 Plymouth Ct., Chicago for many years.

There was one flaw. Nobody (including Mergenthaler Linotype) ever tested the system casting 14 lpm for more than 20 minutes. On extended runs the back knife became very warm and a nodule (knobs) and sprew (trim from bottom of slug) would adhere itself to the knife and weld itself to the knife edge. The next time the knife was crammed against the mold this obstruction prevented the knife edge from riding the mold by a thousandth or so inch resulting in type high to vary anywhere from .918” to .920” or whatever.

It required close attention from the machinist to “mike” the slugs every 20 minutes or so and fill in a log sheet showing reading and time. Every 2 hrs. we removed the back knife, (held in place with 1/2” pivot pin) cleaned cutting edge of knife with a brass rule then applied something called “preventive metal adhesion”, @ $15.00 a gallon sold by Mergenthaler. It looked like black liquid graphite.

We also had 2 sets (34 TTS extra thick spacebands each) for both ACE machines, which were swapped out every 2 hours. The bands would become very hot and get metal buildup on the casting edge of the sleeve which then crushed side-walls of matrices.

We would sharpen a piece of brass rule and proceed to remove the metal buildup from the sleeves. Then the contents in the jar of “black gold” would get painted onto the casting edge of the sleeve. And NO. We didn’t get artist pay. (Whatever that was?)



Water Cooler

This unit incorporates a 1/3 horsepower Hermetic Compressor, blower cooled condenser, cast aluminum cooling tank, seven gallon water storage tank and a valve regulated pump which permits adjustment of water discharge pressure to the exact requirements of the slugs being cast.

A thermostatic temperature control maintains optimum water temperature in the storage tank. A single re-circulating water cooling unit can maintain sufficiently low water temperature for good casting quality with a thermal load for four molds in continuous operation. A full complement of safety devices is provided, including a "Klixon" thermal overload protector for the compressor and fan motors, a relief valve to prevent excessive back pressure at the pump when the Linotype flow control valve is shut off and a circuit breaker which cuts off all power if the pump motor is overloaded. An armored hose is supplied with the Thermex disk for tap water installations; inlet and outlet hose-connecting "T" adapters (supplied) will permit the use of standard Mergenthaler hydraulic hose and provide for branch connections to several disks. Dimensions (approx.): 36” wide x 26” high x 12” deep.