Extrusion Press Container



The container is one of the main elements for the performance of the extrusion process. The container mantle has the function of supporting the liner in order to prevent a breakage of the liner under high extrusion pressures. The pressure needs to be distributed homogenously from the liner to the container. And this is possible with a proper shrink fitting process. Naturally will the shrink fitting constitute a pressure on the container due to the squeezing of the container by the shrink fitted mantle. Finally is this external pressure there in order to balance the generated pressure during the extrusion. The support needs to be continuous and homogenous distributed during the whole extrusion.

An interruption of this support can cause the exceeding of the plastic flexion limit of the container and a resulting deterioration of it.


The temperature of the billet should be controlled as of it is taken out off the oven until it passes through a homogenously heated die. And the easiest way to do this is to correct a variation of the container liner instantly when it incurs. As a result a serious saving will be achieved in terms of the required energy.


The necessary time for responding to the heat demand is proportional to the distance between the temperature sensor and the heat source. At Damatool Containers, which typically have both vertical and horizontal four temperature control zones, the cartridge type heaters are positioned in the proximity of the liner. The purpose of this is primarily not to heat the mantle, but the liner and thus to maintain a consistent billet temperature when the alloy enters into the die. Special designed thermocouples are used in order to monitor simultaneously the temperatures of both the liner and the mantle.

The heating elements are positioned in the proximity of the temperature sensors. The rapid response to temperature increase and decrease ensures a consistency of the liner temperature. In practice, also excessive heating, annealing and softening risks of the mantle are eliminated. And the operating costs are minimized since the heat demand is met such fast.

The viscosity of the alloy to be extruded is extremely sensitive against heat. Notwithstanding, the die designers have to assume that the die will always remain at homogenous and optimal processing temperatures during the extrusion. The temperature at the exit end of the container liner has a sudden change effect on the temperature of the die. The thermal mass of an extrusion container is much higher than that of the die package. The heat transfer starts as soon as the die gets in contact with the liner end and rapidly continues until a thermal balance is achieved. The liner temperature, which has such an influence on the die temperature, needs to be monitored closely.

The temperature, incurring at the bottom of the mantle will rise up inside the container holder and increase the temperature at the top considerably when this is not monitored closely at particularly large containers. Under normal conditions is the vertical temperature difference at the liner exit in conventional containers between 75-110°C .


Thermal measurements have proved that the temperature difference between the top and the bottom of the die is approximately equal to the temperature difference between the top and the bottom of the liner exit during the extrusion. At the same time have the experiences have shown that the profile output lengths at the upper holes of a multi-figure die are approximately 1% higher per each 5°C vertical temperature difference than the profile output lengths at the lower holes. This constitutes a serious problem for both the operation of the puller and for that the shearers are able to cut the correct lengths. As a result will this situation becloud the sustainment of the expected tolerances from a high sensitive profile with vertical components.

Not only the contact of the container liner influences the die vertical temperature difference, but the vertical temperature difference increases further by the effect of the die stack.


The mass of the die shuffle, in which the die is seated, is sufficient to take the heat from the lower half of the die. Therefore, the equalization of only the temperatures of the lower and upper edges of the liner will not be sufficient to eliminate the unequal outputs completely.  The liner temperature must be a little bit higher at the lower part compared with the upper part in order to eliminate any vertical temperature variation at the die exit.

The Damatool Container eliminates the vertical temperature difference problem at both the liner and the die by utilizing 2 temperature control zones at the top and the bottom. Thus, the speed of the product exiting at the top or bottom of the die will be equal.

The basic technical feature of the Damatool Container is its ability to control the temperature of the die entering billet from the beginning until the end of the extrusion. Nevertheless, a healthy control is only possible with a well operating Dummy Block. The Dummy Block pushes the billet inside the container and withdraws then by leaving a thin layer of aluminium on the liner wall. The successful interaction between these two components has a critical importance for a better extrusion. The efficiency of each should not be measured separately, but along with the other interacting components.


The experiences have shown that the Damatool Container, designed to heat the liner primarily and not the container mantle, can decrease the costs of the utilized energy by up to 75%. At the same time are also long termed savings provided with extended mantle life-time. Mantles will maintain their hardness by eliminating excessive heating. Extreme internal thermal stresses, possible to result in cracks, are thus eliminated. Also due to vertical temperature differences at the dies possible to incur scraps are avoided. Extrusion products can now be produced in accordance to the profile tolerances and at speeds, which were not possible until present. Whilst extrusion companies sell their products length based, they gain the advantage of saving from costs by producing close to the minimum tolerances.


Container Liner

The liner mainly resists during the extrusion against the wearing effects of metals and metal oxides. Preserving the hardness at high temperatures is only possible by decreasing the flexion. That’s why the liner needs the support of the container against breakages.


The mainly material features of the container liner are that it has a high hardness, high resistance, a very low flexibility structure. We suggest AISI H13 (DIN 1.2344) or DIN 1.2367, a derivate of H13, as the container liner material.


The shrink fitting method provides that the container holds the liner. The liner is subjected to a circular load, a friction between the container and the billet. The shrink fitting method is applied in order to prevent any slipping between these two parts. The shrink fitting ratio is calculated according to the inner diameter size of the container mantle.


Potential reasons for damages;

The liner might be damaged due to following reasons;


Thermal shock: The liner is very sensitive against any thermal shock. Any sudden heating up or cooling down can cause cracks.


Support deficiency: The liner should be fully supported by the container. This means that the shrink fitting should be performed properly, otherwise deteriorations will incur due to stresses during the extrusion. A higher container temperature than the liner temperature will eliminate the provided support.


High temperature: The liner material will soften at high temperatures. As a result pre-mature wear will be observed. Temperatures at normal values will ensure a longer life time and savings.



Measures for preventing damages and extending the liner life time;

  1. Heat up the liner prior to the usage. A slow heating up (60°C/hour) is recommended.
  2. Be sure that the pre-heating process doesn’t harm the shrink fitting tightness.
  3. Provide that the liner remains warm when the extrusion press is not operating.
  4. Be sure that the container temperature doesn’t exceed the liner temperature.
  5. Avoid a direct fire contact.
  6. Do not weld.
  7. Be sure that the die side contact surface is clean.


Extrusion Container Care and Maintenance

In fact, the extrusion press is performing a serious job. That’s because high pressures are applied on its main parts. The tie rods and the main cylinder are stressed, the front press plate yields and the liner is subjected to a radial pressure at each pressing.


That the container and liner unit are flexible sets means that they have a definite life time. At the same time, these parts of the pres are the candidate parts for the most wear. When we except the die part, the container and the liner are parts subjected to operate continuously at high temperatures. The stem heats up, too, but this happens by the half of the temperature of the container. Yield can be obtained from the container and liner duo, forced to provide a performance under the combination of high pressure and temperature, by following definite procedures only.


The following are the most frequent pre-mature container and liner deterioration reasons;

  • Improper pre-heating
  • Overheating
  • Metal fatigue cracks
  • Faulty alignment setting between the container and the stem
  • Faulty alignment setting of the tie rod
  • Limited bearer space between the liner surface and the die
  • Aluminium accumulation on the die surface
  • Dent front platen or front plate platen




Pre-heating: Let’s first look at the details related to the heating-up of a new and cold container. The most preferred pre-heating method is to heat-up in an oven with a proper operating temperature control system. Ageing and die ovens can be preferred in the absence of such an oven, too.

The container will reach a value of max. 200°C in an ageing oven. The achievement of a temperature above 400°C may be possible after having fitted it on the press. When heating-up the container in environment temperatures on the press, it should be left until 200°C for 15 minutes every 60°C in order to achieve a thermal homogenization. For temperatures above 200°C, the container should be left for 30 minutes every 60°C. During the heating process, thermocouples should be placed such to measure both the liner temperature and the container mantle temperature. The container should never be taken to production at temperatures below 370°C.

Overheating: The evidence for overheating is the erosion look on the external surface of the container. In most cases is overheating responsible for the decrease of the container’s hardness. And in exceptional situations will this even result in the complete blowing up of the container, too.  The decrease of the hardness of the steel incurs by the effect of time and temperature duo. Even if the annealing initiation temperatures of H11 and H13 steels should be 600°C, the operation at lower temperatures can have an annealing effect, too. It is necessary to operate the container mantle at temperatures close to 400°C as far as possible. Overheating is commonly the result of an insufficient or totally uncontrolled heating system.


Latest developments in container design;

Many containers were being heated up with electrical heating elements placed into the container holder in the past years. But the requirement to achieve a more homogenous container temperature by time and the longer container life time demands of the extruders have resulted in the development of the internal heating system for the container mantle.

Another application, developed in order to achieve a homogenous temperature value in the container, is the multi-zone temperature control system. Many of the new produced extrusion presses containers are divided into 2 or 3 zones in the vertical and into 2 zones in the horizontal as the lower and upper zone. The usage of a separate thermocouple for every zone provides the prevention of overheating. We should remind that axial temperature differences generated along the liner incur due to the heat losses at the edge sections of the container. And this can result in overheating and expansion in the central zone of the container.


Very less old type extrusion presses have multiple thermocouples in order to control the temperature of the container. The increase of the complaints related to short container life time has resulted in that the manufacturers have added a second thermocouple in order to track the container temperature by time. The set values of thermocouples are determined as to be 400°C on the stem side and 420°C on the die side. The isothermal heating system automatically shuts off when these values are achieved. If you shouldn’t have an overheating protection system, you can contact us in order to procure one as soon as possible.

Presently are all press containers manufactured with 2, 4, 6 or 8 zone temperature control systems. Another current feature of the containers is the air cooled liner. This method is designed in order to increase the production amount and quality. It is at the same time useful for maintaining the container at the desired temperature range. You might desire to benefit from the advantages of new technology containers if you have an old type press. You may contact us for a zone controlled heating system application and liner changes.



Metal fatigue crack: The crack, having may reasons, commonly starts from the wedge runnel. And the most common reason is losing the hardness and this incurs due to high temperatures. Another reason is production failure. There should be no sharpness at the corners on the inner surface. We complete the production at container manufacture by applying the most appropriate radius value. If though cracks develop around the lifting and thermocouple holes, this again indicates that the container has lost its hardness and an expansion has developed as a consequence of this. The crack incurs only when the container is used sufficient enough to lose its hardness. The development of a crack means that the container has completed its life-time.


Centre alignment failure between the stem and the container wasn’t of critical importance years ago. That’s because dummy blocks were not wide spread at that time. The meeting of the container at the centre with the die, the stem, pushing the billet along the liner hole, and self centring shim were sufficient for that time. Presently, a nearly commonly accepted dummy block mandates a fully centred container and extrusion press. The dummy blocks we produce are designed such to tolerate as minor acceptable centre misalignments. This situation of course doesn’t excuse the non-performance of a proper and fully centre alignment. A centre misalignment can cause the fracture of small particles due to crash of the liner on the entrance surface. And the longitudinal scratches on the liner inner surface indicate that the container is not in the press centre.


Container cooling. Air cooled liners are offered optionally at many new presses. The cooling is performed basicly by the flow of the pressurized air trough the ducts around the liner. The air flow is generally controlled by PLC and is effective in an average temperature range of 10°C. Some experienced operators of the sector critisize this design as follows: "The real stunt is not to increase the Container and Liner temperatures at levels which requires to decrease them." Though that have companies, which manufacture at critical tolerances, have noted that they benefit from liners with air ducts.

Potential reasons for container damages:

Thermal shock: sudden heating up or cooling down can cause tensioning and cracks of the container mantle.


Extreme heating up: The container will soften and weaken at high temperatures. A permanent softening is to be observed when the container temperature reaches 600°C. This converts the container unusable.


Non-homogenous heat distribution: Heterogeneous heat zones may develop on the container during the extrusion. The high temperature zone commonly develops in a region close to the centre. The resistance will decrease in the container zone with a high temperature region and a “bulge” event may incur. This expansion is permanent and can only be eliminated by machining.


In order to preserve the container against damages:

  1. Heat up the container prior to the usage.
  2. Perform the temperature increase slowly (60°C/hour).
  3. Avoid a direct fire contact.
  4. Deem welding as the last option. When you must, perform the welding after heating up the container up to 550°C and then apply distressing.
  5. Don’t subject it to sudden cooling down.
  6. Check the thermocouples frequently.

Preventive Check-List for containers:

  1. Check the centre adjustment of the press.
  2. Check the thermocouples at least once a week.
  3. Check the container on whether there are surface cracks or not.
  4. Check the container hardness at every liner replacement.
  5. Grind the container inner surface at every liner replacement.
  6. Immediately repair when there should be any partial movement of the container should be observed inside the container holder.
  7. Perform machine cleaning against metal accumulation at the container entrance and exit surfaces.


Advantages of Damatool Containers

  1. Provides a homogenous alloy flow through the die.
  2. Decreases operating costs.
  3. Decreases wastes.
  4. Decreases waiting times.
  5. Increases productivity.
  6. Allows isothermal extrusion.
  7. Increases life-time.


Damatool defines a further standard of excellence in the extrusion sector with its smart container design.


*The results may vary according to the individual pres features and the installation.