GenFreeze answers a narrow question: does the material still behave once it is cold. The chamber holds a low temperature while the beater and flexing grip work the specimen inside it, so the part is bent at the temperature it will actually meet in service rather than at room temperature. Rubber, leather, plastics and PU leather all go in, and the fixtures can be set to the position the test calls for.
There is a longer write-up of the method and of this tester in our blog.
The two models differ in how the chamber is laid out and how much floor it takes. GenFreeze-H is the horizontal cabinet, two metres wide; GenFreeze-V stands upright and takes about half that width for a chamber of nearly the same size.
| Item | GenFreeze-H | GenFreeze-V |
|---|---|---|
| Material | Stainless steel 304 | Stainless steel 304 |
| Controller | PID control | PID control |
| Temperature range | RT to −30 °C (I), RT to −50 °C (II) | RT to −30 °C (I), RT to −50 °C (II) |
| Temperature uniformity | ±1 °C | ±1 °C |
| Cooling speed | RT to −30 °C within 60 min | RT to −30 °C within 60 min |
| Refrigerant | R404 | R404 |
| Compressor start delay | 8 min | 8 min |
| Inner box action | Finished shoe bending, sole flexing, leather flexing and vamp flexing fixtures, or custom-made | Finished shoe bending, sole flexing, leather flexing and vamp flexing fixtures, or custom-made |
| Safety devices | Thermal, overheat and overload protection | Thermal, overheat and overload protection |
| Insulation | Rigid polyurethane foam and glass wool | Rigid polyurethane foam and glass wool |
| Viewing window | Two, 0.4 × 1.4 × 10.6″ (10 × 35 × 270 mm), double-layer vacuum glass | Two, 0.4 × 1.4 × 10.6″ (10 × 35 × 270 mm), double-layer vacuum glass |
| Motor | Gear reducer motor, no belt | Gear reducer motor, no belt |
| Counter | LCD 0 to 999,999 with power failure recovery | LCD 0 to 999,999 with power failure recovery |
| Interior dimensions | 23.6 × 23.6 × 19.7″ (60 × 60 × 50 cm) | 23.6 × 23.6 × 21.7″ (60 × 60 × 55 cm) |
| Dimensions (W × D × H) | 78.7 × 30.7 × 39.4″ (200 × 78 × 100 cm) | 43.3 × 41.3 × 63″ (110 × 105 × 160 cm) |
| Weight | 882 lbs (400 kg) | 926 lbs (420 kg) |
| Power | 110 V / 60 Hz or 220 V / 50 Hz | 110 V / 60 Hz or 220 V / 50 Hz |
Tell us the lowest temperature you need to hold and the fixture your specimen calls for, and we will confirm the configuration. A quick request online is the quickest way in.
Need Additional Quality Control Equipment to Build Your Laboratory?
Low-temperature testing is only one part of a complete quality control laboratory. NextGen can help you equip your entire lab with rheometers and viscometers, abrasion and flex testers, ageing and salt spray chambers, hardness and rebound testers, specimen cutting presses, and other supporting solutions, all coordinated as one complete project.
GenFreeze answers one question for a materials laboratory: does the product still behave once it is cold. The chamber holds a low temperature while the beater and the flexing grip work the specimen inside it, so the part is bent under the conditions it will actually meet in service.
That is the difference between this instrument and a cold store. Conditioning a specimen in a freezer and then flexing it on a warm bench measures a material that has already started to recover, and the thinner the sample the faster that happens. Here the cold and the mechanical work happen in the same place at the same time.
We supply it mainly to footwear, automotive and general rubber laboratories that have to demonstrate cold performance rather than assume it.
There is a longer write-up of the method in our blog.
Rubber, leather, plastics and PU leather.
Footwear is the usual application, because a sole or an upper is expected to keep flexing through a winter without splitting, and a compound that passes at room temperature can fail badly at -30 °C. The same argument applies to any part that is bent in the cold: seals, gaiters, hoses, conveyor covers and moulded protective components.
Because the fixtures set the way the specimen is held and bent, the practical limit is usually the shape of the part rather than the family of material it belongs to. Both finished products and material level specimens are tested on the same machine.
The rest of our rubber testing range covers the ambient temperature side of the same programme.
Rubber and polyurethane stiffen as they cool. A compound that survives a hundred thousand flexes on the bench can crack in a few thousand at -30 °C, because the same bend now puts far more strain into a stiffer material and the material has less capacity to absorb it.
Testing warm therefore proves the wrong thing for a product sold into a cold climate. It answers a question about the laboratory rather than about the market, and the failures show up later as warranty claims from a single winter.
The cold chamber is what turns a flex test into a statement about winter service, and it is why cold flexing appears in footwear and automotive specifications as a separate requirement rather than as an option.
How far the compound has stiffened before it cracks is measured separately, on a temperature controlled hardness tester.
The layout and the floor space, not the climate. GenFreeze-H is the horizontal cabinet at 78.7 × 30.7 × 39.4″ (200 x 78 x 100 cm); GenFreeze-V stands upright at 43.3 × 41.3 × 63″ (110 x 105 x 160 cm).
The chambers are almost the same size: 23.6 × 23.6 × 19.7″ (60 x 60 x 50 cm) inside the horizontal model and 23.6 × 23.6 × 21.7″ (60 x 60 x 55 cm) inside the vertical one. Weights are 882 lbs (400 kg) and 926 lbs (420 kg). Every climate figure, from the temperature range to the cooling speed, is identical between them.
The choice is therefore made by the room. Where bench frontage is the constraint, the vertical model takes about half the width for the same test volume; where headroom is limited or the cabinet has to sit under services, the horizontal one is easier to place.
Send us the space you have and we will say which cabinet fits. A short enquiry with the room dimensions is enough.
Two chamber options are offered: room temperature down to -30 °C, and room temperature down to -50 °C.
Both models accept either option, so the decision is about the lowest temperature your specification asks for rather than about the cabinet you choose. The -30 °C build covers most footwear and general rubber work; the -50 °C build is specified where a customer qualifies parts for arctic or high altitude service.
It is worth checking the standard rather than the habit of the laboratory here. A specification written around -40 °C cannot be satisfied by a chamber that stops at -30 °C, and retrofitting the colder refrigeration package later is not a straightforward change.
Which option suits you depends on the standard your parts are qualified to. Send it over with a quotation request and we will confirm the configuration against it.
Room temperature to -30 °C within 60 minutes.
That figure decides how a working day is planned as much as any other specification on the machine. A chamber that takes an hour to pull down is loaded in the morning and kept cold through the shift, rather than cycled between specimens, and the test plan is built around that rhythm.
It also sets expectations for the first run of the day. Specimens have to reach temperature themselves once the chamber has arrived there, and a thick sole or a finished shoe takes noticeably longer than a thin strip of material.
Our write-up of the method follows a full run from loading to the first crack.
Temperature uniformity is ±1 °C.
It matters because a flex test compares specimens with each other. If one corner of the chamber sits two degrees colder than another, part of the scatter in the result belongs to the cabinet rather than to the compound, and no amount of repeat testing will separate the two afterwards.
A degree is not a small thing near the glass transition of a compound, where stiffness changes quickly with temperature. That is exactly the region cold flex testing is aimed at, so uniformity is worth checking against the tolerance your specification allows rather than treated as a formality.
Where several specimens run together, positioning them consistently in the chamber from batch to batch removes another source of variation.
The refrigeration circuit runs on R404.
It is a common commercial refrigerant, which is the practical point for a buyer: the chamber can be serviced by a refrigeration engineer anywhere without a specialist gas being shipped in, and spare parts for the circuit are ordinary trade items.
The unit that uses it is sized for the pull-down quoted on this page, room temperature to -30 °C in an hour, and for holding that temperature while the mechanism inside the chamber is running and adding heat.
As with any refrigeration equipment, service intervals and local regulations on refrigerant handling are worth confirming with your maintenance provider when the machine is installed.
The compressor has an 8 minute start delay.
A delay after shutdown is standard protection on a refrigeration unit. It allows pressures in the circuit to equalise before the motor takes load again, and starting against unequalised pressure is one of the reliable ways to shorten the life of a compressor.
In daily use it means the chamber should not be switched off and straight back on between specimens. If a test has to be paused, leaving the refrigeration running is both faster and kinder to the machine than a stop and start.
It also explains an eight minute gap that occasionally puzzles a new operator: the machine is protecting itself rather than failing to respond.
The inner box takes finished shoe bending, sole flexing, leather flexing and vamp flexing fixtures.
Between them those four cover most of what a footwear laboratory is asked to demonstrate: the complete product, the component that carries the flexing, and the materials that go into the upper. Each holds the specimen in the way its own test method describes, which is what makes results comparable with another laboratory.
Custom fixtures are made as well, and that is the usual route when a part does not fit any of the four or when a customer specification describes its own arrangement.
Send us the specimen drawing and the bend the standard asks for, and our team will confirm what can be built.
Yes. Fixtures are custom-made when the standard four do not suit the specimen.
The practical limits are the interior size, 23.6 × 23.6 × 19.7″ (60 x 60 x 50 cm) or 23.6 × 23.6 × 21.7″ (60 x 60 x 55 cm) depending on the model, and the movement the beater and the grip need around the part. A fixture that fits the chamber but leaves no room for the mechanism to travel is not a working fixture.
Both are worth checking before the order rather than afterwards, because the chamber size is fixed and the fixture is the flexible part of the arrangement.
Ask us for a configuration with the drawing attached and we will come back with what is possible and what it involves.
Yes. There are two viewing windows of 0.4 × 1.4 × 10.6″ (10 x 35 x 270 mm) in double-layer vacuum glass.
The double glazing is what keeps the window clear at low temperature instead of frosting over. A single pane in a chamber at -30 °C becomes opaque within minutes, which defeats the purpose of having a window at all.
Being able to see inside matters more on a flex test than on most laboratory work. The result is the cycle count at which a crack appears, so the first crack has to be spotted without opening the door and losing both the chamber temperature and the condition of the specimen.
The two windows also make it practical to check several positions in the fixture without moving the machine.
An LCD counter runs from 0 to 999,999 and recovers after a power failure.
The recovery function is the part that matters on a long run. A flex test that has been going for two days does not have to be started again because the building lost power for a minute, and the count that is reported is still the count the specimen actually saw.
Six digits is enough for the cycle counts used in footwear and rubber flexing specifications, which typically run into the tens or hundreds of thousands rather than beyond a million.
For record keeping, the counter reading is what goes into the report together with the temperature and the fixture used.
Thermal, overheat and overload protection.
Together they cover the two ways an unattended chamber gets into trouble: a fault in the temperature control that runs away, and a mechanical jam that loads the motor beyond what it should carry.
This matters because flex testing runs long. A machine counting toward several hundred thousand cycles is left alone overnight and over weekends, and the protection is what decides whether a fault simply stops the test or damages the machine and the specimens with it.
As with any laboratory equipment left running unattended, local rules about out-of-hours operation are worth confirming with your safety officer.
Rigid polyurethane foam and glass wool.
Insulation decides how hard the refrigeration has to work to hold -30 °C, and therefore how stable the temperature is over a long run and how much power the machine draws to keep it there. A poorly insulated cabinet reaches the set point and then fights to stay at it.
It also decides how much condensation and frost forms on the outside of a cabinet standing in a warm laboratory, which is a housekeeping matter but a real one where the machine sits next to electrical equipment or on a finished floor.
The combination used here is the conventional one for chambers in this temperature range and is chosen for stability rather than for a specification sheet.
A gear reducer motor with no belt.
A belt drive changes speed as it wears and slips, and a flex test is counted in cycles, so the drive has to hold its rate through hundreds of thousands of them. Removing the belt removes that drift, and it removes one of the wear items that would otherwise need attention during a long programme.
It also makes the machine quieter and less prone to the sudden stoppages that a slipping or broken belt causes halfway through an overnight run.
For the laboratory the benefit is straightforward: the cycle count on the display means the same thing at the end of the test as it did at the beginning.
Stainless steel 304.
It is the usual choice for a chamber that runs wet as well as cold. Condensation and frost form on every cold surface, each defrost leaves water behind, and a plain steel interior would not survive many cycles of that.
It also wipes down without absorbing anything from the specimens, which matters when leather, treated materials and finished footwear go into the same chamber over the life of the machine.
Stainless steel is more expensive than the alternatives at the point of purchase and cheaper over ten years of use, which is the trade a laboratory buying a chamber is really making.
110 V / 60 Hz or 220 V / 50 Hz.
Both models are available for either supply, so the machine matches a North American or a European laboratory without a transformer standing beside it.
Confirm the supply at the bench before delivery. A chamber of this size is not moved easily once it is installed, and the refrigeration unit draws its highest current during pull-down rather than while it is holding temperature, which is where a shared or undersized circuit shows up.
Tell us which supply you have when you enquire and we will configure the machine accordingly before it ships.
The horizontal model measures 78.7 × 30.7 × 39.4″ (200 x 78 x 100 cm) and weighs 882 lbs (400 kg). The vertical model measures 43.3 × 41.3 × 63″ (110 x 105 x 160 cm) and weighs 926 lbs (420 kg).
Add clearance for the door to open fully and for service access to the refrigeration side. A cabinet pushed tight into a corner is difficult to maintain and runs warmer, because the condenser needs air around it.
Weight is worth checking against the floor if the laboratory is above ground level or the building is older. Four hundred kilograms on a small footprint is a significant point load.
Our team can go through the layout with you before the order is placed.
A Ross flex tester bends the specimen over a rod at room temperature and measures how fast a cut grows. GenFreeze puts the flexing inside a cold chamber and asks a different question: how the material behaves when it is stiff.
The two are complementary rather than alternatives. Cut growth at ambient temperature describes the compound under normal service; cold flexing describes it at the point where the same movement does far more damage.
If you need the Ross method itself at low temperature, that is a third machine again: the GenRoss-CH carries its own low temperature chamber and performs the Ross test inside it.
Which one a specification calls for is usually stated explicitly, and we can confirm it against the standard you work to.
Cold flexing is one leg of a climate qualification rather than the whole of it.
Heat ageing on an aging oven is the other end of the same programme: it shows what the compound becomes after prolonged exposure to heat, which is the failure mode that arrives slowly rather than in the first winter.
Hardness measured at temperature on a digiChamber sits between them and tells you how far the compound has moved before it cracks, and room temperature flex cracking on a Demattia tester gives the baseline all the others are compared against.
Laboratories that run all four end up with a description of the material rather than a single pass or fail.
Both. The fixture list starts with finished shoe bending, so a complete shoe goes into the chamber, and the sole, leather and vamp fixtures cover material and component level specimens.
That combination is what a footwear laboratory usually needs. Material testing tells the compounder what to change, and testing the finished product tells the brand whether the assembled article survives, which is the claim that has to stand up in front of a customer.
What limits the machine is the interior size rather than the type of specimen: 23.6 × 23.6 × 19.7″ (60 x 60 x 50 cm) in the horizontal model and 23.6 × 23.6 × 21.7″ (60 x 60 x 55 cm) in the vertical.
For the Ross method on a finished sole at low temperature, the GenRoss-CH carries that fixture in its own chamber.