METROL SPRINGS LTDManufacturers of Nitro-Springs

Introduction to Metrol Springs

• Metrol Springs Ltd have been manufacturing nitrogen gas springs since 1985.

• Metrol Springs is a private limited company.• Over the past 20 years we have expanded our

production facilities year on year to increase capacity to fulfil the demands for Nitro-Springs.

• After initially supplying the UK pressing industry Nitro-Springs has grown into a global brand represented across Europe, China, Japan, Korea, India, America and South Africa.

Manufacturing Standards

• Metrol Springs Ltd is a certificated ISO 9001-2000 company.

• All Nitro-Spring products conform to the latest Pressure Equipment Directive PED 97/23/EC. The PED sets the most stringent safety standards for pressure vessels ensuring the customer has a product they know they can rely on

All Nitro-Springs are covered by a 2 year warranty or 100,000 stroke meters.

Quality Assurance

• All gas springs prior to despatch must pass 4 individual tests– Load check: this ensures the springs have the

correct pressure.– Stroke test: Every spring is cycled a number of

times, this beds the seal eliminating failure during the first few cycles.

– Leak test: Following the stroke test the spring is covered in leak detector to ensure the seal and valve do not leak.

– Dimensional check: The gas spring is then checked to ensure all dimensions are within tolerances.

Nitro-Springs Approved by:• MG Rover• FIAT• Thyssen Krupp

Automotive• Stadco Pressings Group• LDV Vans• Takao• Futaba• Unipres

• General Domestic Appliances

• Hotpoint• Creda• Wagon Automotive

Group• Lear Corporation• Sertec Group• Gestamp Group

Nitro-Springs have just been approved for use by Renault and VW on dies manufactured by the Gestamp group

Approvals for Gas Springs manufactured by Metrol Springs under other brand names

• Toyota America• Tower Automotive• Lear corporation

Design features for improved durabilityNitro-Springs have the following features to increase the durability and life of the spring.

– Latest seal technology with low friction profiles.

– Teflon coated steel bush for guidance (ISNG,MO, MA ranges)

– Side force elimination base design.

– Teflon additive included in the oil to reduce friction.

In addition all Nitro-Springs are 100% tested before leaving the factory to guarantee you will receive the product in perfect working order..

Wiper geometry and position ensures that oil and debris does not pool around the top of the seal unit which can

be sucked into the spring during operation.

– Nitro-Spring– Oil and debris are removed

from the piston surface and flow away

– Other manufacturer

– Wiper and seal unit design allows oil and debris to collect around the piston which can lead to contamination in the spring

Safety Features

• Nitro-Springs are designed and manufactured to be as safe as possible

• Welding is certified by Zurich and samples regulary tested in the laboratory.

• All materials delivered are accompanied by mill certificates and our ISO system enables full traceability of every single component in the gas spring.

• Manufactured to conform to the PED97/23/EC saftey standards for pressure vessels

Additional Safety Features

• Piston anti ejection clip

• If seal unti is inserted the wrong way up –– Groove prevents seal unit

from coming out of the cylinder

– O-Ring groove designed to vent gas if inserted upside down

Overhaul and Maintenance• Nitro-Springs are designed to be low maintenance

and easy to overhaul.• Replacement of the seal kit is cost effective • Unlike many other manufacturers our overhaul

kits contain a new seal unit complete with new seals, o-rings and wipers. Experience has shown that there is little benefit in using the old seal unit and trying to fit new seal components as they are often damaged during assembly causing the spring to leak.

• Nitro-Spring tool kit contains all the necessary equipment for the maintenance and overhaul of our gas springs and gas spring systems

Nitro-Springs Factory Toolkit

Overhaul Kit – with complete seal unit, oil, replacement clip, dust seal plug and valve

Introduction to the Nitro-Spring Range of Gas Springs

Range selection

• The following information will give you a guide to each different range.

• It is important to select the appropriate range for each application in order to get the maximum life from the spring.

• ISNG Range– ISO-9011-1 gas spring standard– Contact force range from 250kg to 10 tonne– Stroke lengths up to 300mm– Can be linked in series– Optimum design for gas springs to be used in all

applications

• LFNG Range– Low force increase gas spring– Contact force range from 500kg to 5 tonne– Stroke lengths up to 300mm– Can be linked in series– To be used in applications where the force increase of a

standard gas springs will cause a problem with the component quality

• MO Range– High tonnage compact spring– Contact force from 500kg to 12.5 tonne– Stroke lengths from 25mm to 160mm– MO1750 and above can be linked– For applications where high tonnage is required and height is

restricted

• MA Range– Compact range of standard force spring– Contact force range from 500kg to 12.5 tonnes– Stroke lengths up to 50mm– MA1500 and above can be linked– To be used where standard force is required, short stroke and

height is restricted

• EX Range– Ultra compact high tonnage spring– Contact forces from 360kg to 6.6 tonne– Stroke range from 10mm to 125m– Can be linked in series– To be used when high tonnage is required and height is restricted

• HDG Range– Ultra high tonnage compact spring– Contact forces from 420kg to 18.3 tonnes– Stroke range from 6mm to 50mm– To be used where short stroke is required and a very high tonnage

and both diameter and height is restricted.

• Mini Nitro-Springs– Low force gas springs– Variable pressure up to 200kg contact force– Stroke range from 10mm to 125mm– Ideal replacements for die springs– Ideal for use as ejectors

Introducing the New EX RangeFrom Metrol Springs Ltd.

Manufacturers of Nitro-Springs

EXtra Tonnage – EXtra Compact

• ISNG1500/50 – 1500KG / 210mm Length• EX2400/50 - 2400KG / 145mm Length

EX Gas Springs – Giving More for Less

• The EX Gas Springs give you considerably MORE tonnage in LESS space than standard or other “compact” gas springs.

• Consider the following and you can realise how the EX Range can really save you money

• Less springs required due to more force per spring.

• Less machining and lower tool heights• = Reduced tooling costs.

EX Range –New Piston Technology

• The EX Range uses new piston technology to create a hardened piston rod that is resistant to damage.

• The resistance to surface damage reduces gas leakage during the operating life of the spring.

EX Range – New Sealing Technology

• The EX Range of gas springs has been designed using the latest in sealing technology.

• The specially designed seals have a smaller sealing area, reducing friction yet remaining as reliable as any other seal.

• The reduction in friction reduces the operating temperature of the gas spring thus increasing the life of the seal.

• A special additive is used in the Nitro-Spring lubrication oil. The additive further reduces the friction and thus heat build up during operation.

• This combination results in a considerable increase in the life of the main seals in all of our Nitro-Spring Products.

EX Range -Link Systems

• The EX Range has been designed so that all models can be piped to a control panel without any modification

• The EX range is linked using our standard CNOMO pipe system

EX Range – Maintanence

• All EX gas springs are serviceable and can be overhauled using factory supplied kits.

• For companies who specify Nitro-Springs in tooling standards we offer a Factory Consignment Stock of overhaul kits. Please ask for details.

• Reduces maintenance costs.

EX Range – Safety and Peace of Mind

• All our Nitro-Spring products are fully PED compliant conforming to the latest European safety standards. Nitro-Springs are manufactured according to our ISO9001 quality system.

• The EX range is covered by our standard 2 year guarantee.

• Full PED certified gas spring training courses are available.

Advantages of Nitrogen Gas Springs

Gas Springs require no pre-loadingThe rated force of the gas spring is achieved as soon as the piston rod starts compressing, eliminating the need for preloaded pressure pads.No devices required to preload, guide and seat for gas springs.

Failure of a spring. When a die spring breaks fragments of the material is scattered across die which can cause considerable damage.If a gas spring looses all pressure then the piston simply falls into the body

Easy maintenanceGas Springs can be easily repaired by replacing the seal unit increasing the overall life of the unit.

Flexibility in press selectionPress markett patterns limit tools to certain presses, by using gas springs the tool can be run in most presses increasing the versatility of the plant and reducing the impact of press breakdown.

More compact than mechanical springs

• For the same stroke capabilities Gas Springs are considerably more compact that mechanical springs. The result is more compact tool construction saving money

• Example• EX1000/75 – 75mm stroke,

overall length 188mm• Yellow 50x305 – 76.3mm

maximum deflection, overall length 305mm

More Force than mechanical springs

• Gas Springs produce much higher forces than conventional springs, this means less springs in a tool reducing the number of spring pockets and machining required.

• Example• HDG47/25 – 66000n maximum

force• To equal this force 7 x yellow

50x254 are required

Gas Springs piped in seriesPressure can be easily adjusted through the control panel.Gas Spring pressure can be monitored from the control panel on the outside of the die, no dismantling of the die required.Gas Spring systems can be fitted with pressure sensors, should a leak occur and pressure is lost then the sensor will stop the press, reducing scrap parts and any possible damage to the tool.

Optimising Gas Spring Performance and Durability

• Nitro-Springs are designed and manufactured to give you years of trouble free service.

• It is up to the tool designers, toolmakers and end users to follow the guidelines to ensure that you receive the best possible life from the springs

General user informationAll Nitro-Springs are factory tested prior to dispatch and will give the user

many years of service. To receive the best possible life from the gas springs, the following should be adhered to:

•        Wherever possible retain Nitro-Springs in a positive way, i.e. Use tapped holes or a suitable flange mounting.

•        Ensure that the spring is mounted parallel to the direction of the movement.

Make sure the piston top is perpendicular to the direction of movement

Side forces on gas springs must always be avoided.

•        The tapped hole in the piston rod is to be used only for maintenance and should not be used for mounting purposes.

•        Never use a gas spring where the piston rod could be freely released from the closed position.

•        Where possible the piston rod should be protected from potential damage whilst in use.

The mounting position and method can greatly affect the gas spring life.

  There are 6 main ways to mount a gas spring. Wherever possible it is best to use mounting positions 1,2 and 3 as these retaining options give optimum spring durability. See sheet 3

       

Different mounting options available

The table below is for ISNG style gas spring only. The mounting positions apply to all of the gas spring ranges.

•        During production protection from press lubricants and contamination is advised. If unavoidable drainage holes should always be used to avoid collection of lubricants. If this is ignored the gas spring could eventually hydraulic and cause irreparable damage to the spring.

•        Avoid grinding dust on any surface of the gas spring.

•        Where possible fit hardened “strike plates” where the gas spring piston contacts.

•        Always keep the striking distance between the end of the piston and the mating face to a minimum. This will cut down any additional forces at the point of initial contact between the piston and “strike plate.” 

 Pipe Systems with Control Panel  •        Wherever possible connect the gas springs in a full loop system. This makes charging and discharging the system much quicker. Also if a hose becomes damaged you are still able to run the system without any problems by removing the damaged hose and recharging to the required pressure.•        Never bend the hoses with less than a 20mm radius.•        Always discharge the pipe system before working on it unless you have adequate Metrol training.Wherever possible fasten the hoses down in a fixed position to prevent trapping.

Stroke length

•        Use of the full stroke (S) is never recommended. As a rule of thumb always leave at least 5mm or 10% margin. This allows for over stroking/setting errors.

•        Over stroking of the gas spring will cause damage to the spring. Wherever possible use positive stops on all tooling to prevent this from occurring.

 

Maximum Speed

•        All Metrol gas springs are design to be used in applications where the maximum piston velocity is 38m/min or less.

 

 

 

 

 

 Maximum Charging Pressure

•        The maximum charging pressure stated in the catalogue and marked on the springs must not be exceeded as it may affect the safety of the product.

•        Unless otherwise specified all springs are delivered at maximum pressure except Mini Nitro springs which are available with variable pressure. (Please note: airfreight orders where springs are filled with holding pressure only)

•        Use Nitrogen gas only when charging

 

 

Operating Temperature

 

•        If the recommended operating temperatures are not adhered to, then the service life of the spring will be affected in a negative way.

•        Recommended operating temperature 0 to 80^C

 

 

Essential Safety Notes

 

•        Caution: High-pressure nitrogen.

•        Do not machine or modify any part of the gas spring.

•        Do not weld any mounting flanges or other equipment to the gas spring.

•        If the piston will not move, assume the spring is fully charged.

•        If the gas spring is damaged, the gas should be immediately vented from the spring. When the spring is emptied it should be disposed of.

•        Dispose of gas springs in component form only.

•        All tooling installed with Nitro springs should be fitted with a visible warning plate.

 

 

Charging, Overhaul and Maintenance of Nitro-Springs

 

•        Before attempting any work on a gas spring or gas spring system the person must have attended and passed the Nitro-Spring training course. Upon completion of the course a certificate of competence is issued.

•        Attempting to perform work on a spring without completing the course may infringe safety and have a negative impact on the life of the product.

•        Overhaul and maintenance instructions are found in the Nitro-Springs service manual. This manual is available to people who have completed the Nitro-Springs training course.

•        USE ONLY NITROGEN WHEN CHARGING – THE USE OF OXYGEN WILL CAUSE AN EXPLOSION!