Deprag's New Adaptive Direct Fastening System is a revolution automatic flow form screwdriving. 

The use of flow form screws into two non-drilled sheets requires high down force and high speed to heat and form the hole.  It is a complex assembly because to achieve optimal cycle times and proper funnel and thread forming, the down force and feed speed needs adjusted during the various stages of the screw assembly so that the funnel and thread forming can be done reliably. 

Traditional systems required numerous pre-tests to determine the timing of the piercing point.  Switching parameters too early leads to improper funnel formation and longer assembly times, too late can lead to thread damage.

Deprag's Adaptive DFS is able to sense the exact piercing point as well as other key stages in the screw assembly and switches parameters accordingly assuring:

• automatic adaptation to variances in the screw and part
• the highest process reliability
• shortest possible cycle times
• optimised funnel forming
• reduced set up times
• a more flexible system
• minimise  damaged threads

Other features of the Adaptive Direct Fastening System are:

• Active nosepiece jaws that hold the screw firmly until drilling has started
• Adjustable down holder force
• High down pressure applied directly in line with the screw
• Head first screw feeding to minimise damage to the screw’s tip
• Fast interchange of the mouthpiece for minimal downtime
• Lock stroke for underfloor applications

Max Speed: 8000rpm, freely programmable

Max torque:  15Nm, freely programmable

Feed stroke:  upto 3000N, freely programmable force and distance

Max Downholder force:  1200N, freely adjustable

Weight: 35kg

Assembly at any angle or upside down.

Maintenance friendly

Complete with industrial PC to set parameters, control the screwdriving and to analyse trends

Why do we need high powered grinders?

The obvious answer is that high powered grinders will save you money. 

• Higher power means you can remove more material or make more cuts per year.  Time is money right?
• Higher power also means that your abrasives will be working at their optimal speed, meaning you get a better finish and your abrasives will last longer.

Apart from this, abrasive manufacturers are coming up with more aggressive disks for faster material removal.  The problem with these new disks is that they will destroy most electric grinders and stall most air grinders because they need a high powered tool to run them.  Some examples are the PFERD ALU-Master, CC-Grind disks and the Maija Frästechnik milling discs. These unique new products offer extremely fast material removal but require high powered grinders.

The PFERD ALUMASTER high speed discs are a unique tool that offers very fast material removal.  It is ideal for use on aluminium because it does not produce hazardous or explosive dust. 

It uses ten replaceable tungsten inserts to machine the aluminium rather than grind it.  This also means that the tool doesn’t clog up.  

These discs suit 115mm or 125mm grinders with a max speed of 13,300rpm and PFERD recommend an air grinder of at least 1000watts or an electric grinder of at least 1400watts

Another new disc that requires a high powered grinder are the Maija Frästechnik milling discs.  These are available for a range of materials including steel, aluminium and titanium.  Maija Frästechnik tested and recommend Deprag Turbine powered grinders for use with their discs.

Cengar started business back in 1954 in Halifax, UK.  They patented the world's first twin piston air hacksaw in 1954, and then updated it in 1964.  Since then they have added new models and worked to improve the power, reliability and vibration levels of it's saws.  Recently Cengar updated it's production equipment to again improve quality and reduce lead times.

You will find Cenagr tools in oil rigs, refineries, fibreglass manufacturers, mines and pallet repair facilities all over the world.  They are used to cut steel plate, angle sections, I-beams, bolts, sections and pipes.  All of Cengars saws have very simple, reliable piston motors which use very little air.  No vanes, no bearings, no gears!  They are ATEX approved for T5, Zone 1 hazardous area use except for the Cengar JSM, which is ATEX certified to M2 for underground coal mine use.

Please beware, there are a number of copies of the Cengar CL50 and CL75. They are copies of the old version of these saws so they do not perform as well and they do not have ATEX approvals.  Spare parts are not compatible with modern Cengar saws, and it is an issue to find spares in Australia.

Assembly Technologies Pty Ltd are the Australian importers for Cengar saws.  We usually have all of the saws, blades and spares in stock.  Repair of the saws is very simple, any air tool repair shop should be able to repair them.  In case you have difficulty, we have a full work shop and are able to repair any Cengar saw.

A quick visit to Youtube shows a few dangerous, slow and really clumsy methods of repairing pallets.  Using long bars to pull apart the broken rungs and bashing in old nails brings a tear to our eyes!  

Using a special crow bar of some kind is labor intensive and danegrous if the operator is not careful.  Banging old nails flat is not a good idea if you are  going to replace the rungs because when you nail it back on the new nail can hit the old one and bounce straight back out.

We see many work shops using electric sabre saws to cut off nails.  It doesn't matter how much they spend on these saws, often they don't even last a year and they are dangerous because the cords can easily be damaged.

Cengar has developed two tools especially for pallet repair shops that are repairing pallets all day.  These tools reduce the operators' fatigue so that they can work longer without slowing down, as well as reducing the risk of injury.

The PL905 air hacksaw is a reliable workhorse that will easily last years of year round single shift work.  It features low vibration, a rugged housing and a simple pistion motor that just keeps on going as long as you have clean air and it is lubricated correctly.

The PS2 pallet spreader effortlessly lifts the pallet rungs enough so that you can cut the nails.  A stopper stops the rung from springing out to hit someone in the face.

We also have pneumatic cutters that work exactly like hand operated side cutters, but they are powered by compressed air and easily will cut the toughest nails.

Stop losing money and putting your team at risk, there is a better way!  Please contact us for a demonstration. 

Short and sweet update.

Deprag have updated their POWER LINE of air motors.  Especially the motors in the 1.6 to 6.0kW range.  The big news is that there are now 12 ATEX approved motors with planetary gearboxes and IEC flanges.  4 of those ATEX approved motors have a working speed at or close to 1500rpm, so these motors will be able to directly replace an electric motor provided the flanges match up.

The best news is that the new motors are cheaper than the old range and in many cases more powerful!

Details in the catalogue here or on the POWER LINE motors page here.

Innovative Sheet Metal Fasteners

Flow Drill Screws, Flow Form Screws

FDS® screws from EJOT and FFS® screws from Arnold have been around for a while.  They offer the benefits of a secure and strong joint from one side between two sheet metals.  A big advantage is that they can join dissimilar materials like aluminium, steel and plastics where spot welding is not possible (they are finding more and more applications in the automotive industry where aluminium and other materials need to be joined).  They also allow the use of thinner sheets without the use of additional hardware to strengthen the joints (this is making them more popular in the whitegoods industries).

The screws form a hole by high pressure and the speed of the screw, the heated material is then threaded and cools around the screw.  The joint is strong, and the unscrewing torque is high.  The thread formed is upto 3 times thicker than the sheet metal.

1. Heating the metal with high end load and high speed screwdriver
2. Penetrating the material
3. Forming of the hole
4. Forming of the screw thread
5. Engagement of the threads
6. Final tightening into the cool thread

Advantages for joining sheet metal:

• No swarf or chips
• Stronger joint, higher screw torque possible
• Higher torque means a larger torque window and less chance of stripping
• Screws can be replaced with standard metric screws
• No additional hardware required to strengthen the joint
• High unscrewing torque and vibration resistance
• Possibility of joining thinner materials
• Possibility to join Aluminium
• Can be accessed from one side
• Possibility to join sheets without pre-drilling (in automated applications)

Unfortunately compressed air turbine powered grinders are overlooked by factories because of their high initial cost compared with cheaper tools.  Here we are going to go through and explain some of the advantages of these grinders andd try to explain how they will actually save your organisation money in the long term.

ELECTRIC VS AIR POWER:

240V electric powered grinders are readily available and reasonably cheap, but iunder the stress of continual use an industrial quality air grinder will always outlast the electric grinder as long as it has a quality air supply.  Air grinders will not be affected by dust in the air, they cannot be overloaded or overheated.  The air grinder will also be lighter than an electric grinder with the same power output.  Especially in the case of 230mm grinder, air grinders are available with higher power outputs.  Please note! Most electric tool manufacturers quote the max power input to their tools.  Air tool manufacturers quote the max power output!  So a typical 1000W 240V grinder will only output 600 to 700W of power.  A 1000W air grinder outputs 1000W as long as you have enough air to run it.

POWER to WEIGHT RATIO:

Often we want maximum power without the weight right?  It's not helpful to have high power and high weight or low weight with low power.  Higher power with lower weight means that the work is done faster and with less fatigue.  Less fatigue means less chance of accidents, less breaks and less down time.

Air powered grinders are often chosen over electric tools because for a given power, the vane motor powered grinder is going to be lighter and smaller than a 240V electric grinder. Smaller and lighter tools mean that the operator is not going to be as tired, he can work longer without breaks and there is less chance of injury.

Turbine powered grinders take this a step further.  For example: 

HIGH POWER

Why is high power more important?              Because it saves you money of course!

• Faster material removal - time is money right?  If your trigger time is 3 hours per day, your extra material removal can be a tonne or more over a year compared to a vane powered tool.
• Optimal cutting / grinding speed means that your abrasives last longer - save over 30% on your abrasive costs if you are using quality abrasives!
  • If low powered tools are used, the speed drops when pressure is applied resulting in faster abrasive wear.  HIgh powered tools with speed governors do not slow down.

LOW MAINTENANCE COSTS

Turbine motors have all the advantages of vane motors - (cannot overload, cannot overheat, not affected by dust etc), but they do not have vanes, which is a wear part.  As long as they have clean, water free compressed air, you can depend on them for a trouble free lifetime whereas vane motors have wear parts - especially vanes, that have to be replaced every so often.

ENERGY EFFICIENCY

Compressed air is EXPENSIVE.  The turbine compressed air motor is already a comparatively efficient air motor (see the above comparisons) which of course means it will cost you less to run your compressor. Deprag has also taken advantage of some of the turbine motor's characteristics to make them even more efficient.

Deprag has included a speed governor in it's range of turbine grinders which means that when the tool is not under load it consumes less than half of the air that it uses when under full load.  As the load increases the govenor progressively opens the air inlet valve, increasing the air supply and thereby increasing the power.  The governor also maintains the correct speed no matter what the load - extending the life of your abrasives.

SUMMARY

To really understand the value of turbine powered angle grinders you need to look past the initial cost, especially if grinding is a big part of your business.  The lifetime cost of every tool has to be considered.  Compressed air, abrasives and man-hours are not cheap and they all add up over time.  Many companies have done the tests and have come to realise that the savings we are talking about are real and significant.  Don't ignore the facts!

Take a look at the Deprag 230mm Turbine grinder in action here: https://youtu.be/sufhzTdhMso 

Whenever power tools are going to be used, the usual safety equipment is required such as goggles, gloves, safety shoes and ear protection the cutting of metal in hazardous areas or for long periods of time also requires additional safety considerations.

Risk of explosion:

When a tool is going to be used in a potentially explosive or hazardous area, it is not good enough to just use a "non sparking air tool".  When a risk assesment is done on any tool going into a hazardous area the basic question to ask is what is the maximum surface temperature of the tool, the blade and the material to be cut?  If explosive gases are present, what is the ignition temperature?  

Most operations will not have the facilities to rigorously test a tool's maximum surface temperature.  All of our air hacksaws are tested according to the European ATEX approvals.  This means that the tools have been independantly tested and have a coded approval marked on the tool showing the temperature class tha the tool is suitable for and what environment it is tested for (eg explosive dust or gas, industrial or mining areas).

Vibration:

Depending on how the saws are used, exposure to vibration levels has to be considered.  This is especially important when the saw will be used non-stop for more than half an hour.  During shut down periods in the oil and gas industries, as well as in production environments it is not uncommon for air hacksaws to be in constant use for 8 hours or more.  

Many tools have high vibration levels and according to European regulations cannot be used for more than an hour without a break.  Exceeding these vibration exposures can lead to vibration related injuries that take years to develop and are among the leading compensation claims in the EU.

Most low cost tools do not even state vibration levels, so a risk assesment should be carried out on the tool to determine whether using it for prolonged periods poses a risk to the operator.

All of our tools have their vibration levels clearly declared in their manuals and catalogues.  From these levels you can easily determine how long the tool can be used before the operator has to take a break.  If you would like more information on the vibration levels of our tools, please do not hesitate to contact us.

Cheap Copies:

Cheap copies of our saws are on the Australian market.  Besides being lower power, quality and life expectancy, they normally do not have ATEX approvals nor do they state their vibration levels.

All of our air hacksaws are ATEX approved and have very low vibration levels.

It seems more and more big brand manufacturers are getting their tools made in China or India with substandard materials and design but still charging premium prices.

We recently decided to offer the PB Swiss Tools range of hand tools. They offer a no compromise, top-of-the line range of hand tools, 100% made in Switzerland. They use the highest quality steels, they feel fantastic in your hand, look great (professional) and they last a lifetime.  We have uploaded a selection of their various screw assembly related hand tools, but the full range also includes striking tools (mallets, punches, chisels etc) as well as special tools like picks, scribes, awls, hose pluckers and titanium tools.

Screwdrivers:

High quality PB Swiss Tools screwdrivers with ergonomic Swissgrip handles.

PB Swiss Tools screwdrivers feature the distinctive Swissgrip handles as well as precise, high quality steel drives.

The Swissgrip handle is made of two components.  It feels good in your hand, is slip free, resistant to oils and provides grip even if you have wet hands.

Allen Keys:  Available in sets or individually.

High quality, Swiss made, colour coded Allen Keys

For every Allen key, the tolerances are guaranteed to be less than a hair width. This perfect dimensional accuracy and the hard and tough special alloying make for precise, durable tools.

Available finishes include:

• High quality chrome plating
• Rainbow finish – colour coded wrenches let you find the right key faster
• Gold plated – for corrosive environments or for that extra touch of class?
• Titanium – totally non magnetic for mining & oil & gas applications

T Handle Wrenches:

Ergonomic cross handle wrenches

Okay so we are biased, but these have to be the best T handle wrenches on the market!  They are tough, the handles are ergonomic – soft non slip grip and they look the goods.

Ratchet Drivers:

Precise, durable and smooth ratchet drive screwdriver

The ideal tool for fast tightening & loosening of screws featuring the famous Swiss Grip handles.  Unlike most other ratchet screwdrivers, these are made to be used every day as you favorite tool, and to outlast your car!

Dirt or dust particles can cause damage to some products or the system into which the sub-assembly will be integrated.

In these situations it is important to avoid abrasion, reduce abrasion or target its removal! These are the basic requirements for screwdriving assembly in clean rooms to ensure the quality of the components to be processed. The DEPRAG CleanFeed Concept provides an overall solution.

Advantage: Integrated design for technical cleanliness. Deprag’s complete program is coordinated for all required individual components,  from the feeder to the screwdriver, semi automatic or fully automatic – all from one source.

Function: The screws are stopped in switch position 1 and the residual dirt is removed from the feed parts  via vacuum suction. The removed dirt particles are then collected in a filter with transparent inspection window and a replaceable filter element. In switch position 2 the cleaned connection element is fed into the screwdriving module (inline version) or prepared for pick up (Pick&Place version).

The components below can be used to obtain an optimal result:

Low abrasion parts feeder

• DEPRAG HSF sword feeder – vibration free screw feeding – therefore no component friction and minimal abrasion

Removes particles for the feed tube

• DEPRAG Particle killer – dirt particles from the feeder are targeted and removed in-line

Clean room pick point for screws

• DEPRAG Clean Pick-and Place unit – Screws are fed to to the pick point in the unit, which also has a vacuum to remove particles

Clean room ready Screwdriver

• DEPRAG SFM-V vacuum screwdriving module, which fits onto the screwdriver – residual dirt is removed by suction via an additional vacuum source when positioning the screwdriver.

Air tools and air motors are still assumed to be safe for use in explosive environments and in underground mines, but are they really?  How safe is “safe”?

The simple answer is yes, in general air tools are safe for use in hazardous areas, but not always.  Many types of cutting & grinding tools are not safe no matter what type of motor they use – for example grinders.  Other tools like drills, hacksaws, impact wrenches and air motors are widely considered to be safe. The issue is how safe are they really?

ATEX approvals show that motors and tools have been tested and are safe to use in the indicated temperature zones.

Depending on the cutting speed, some drills and air hacksaws are not safe for use in hazardous areas at all.  Also the quality of the motor and it’s components can lead to overheating of the bearings.

Some gases and dusts can explode at very low temperatures, for example carbon disulfide can ignite at 90 degC.

So what temperature does the air tool or air motor run at?

Do all air powered motors run at the same temperature?

Of course of course they don’t.

ATEX approvals were introduced in the EU to certify the safety of equipment that is going to be used in hazardous areas.  All tools and equipment that have ATEX approvals are marked with a code that identifies:

• Which zone the equipment is safe to be used
• What temperature range the tool operates
• If the tool is suitable for operations where explosive gas and/or dust is present
• Whether the tools is safe for underground or general industrial use

ATEX approvals clarify whether or not an air tool or air motor is safe to use in a particular hazardous area thereby avoiding assumptions about safety that can lead to serious injuries or catastrophic explosions.

Our full range of air hacksaws are ATEX approved some for underground, but most for above ground use.

Most of our air motors in the Advanced Line and Basic Line ranges are ATEX approved for use around explosive gases and dusts.

Our Undergound mining impact wrenches are also ATEX approved for use in underground coal mines.

Deprag’s Green Energy Turbine generator can be used in either a direct or an indirect configuration.

Direct Configuration:

Direct use of gas turbine generator for green energy

In a direct configuration a high pressure gas is run through the turbine. Electricity, lower pressure and lower temperature gas is the result.

Some examples include:

• Energy recovery in metal smelters
  

  Turn wasted hot compressed air into electricty

   

  • often molten metal is cooled by compressed air.  The compressed air flows through cooling tubes and is normally exhausted to the atmosphere.  The hot, compressed air can be run through the GET and the recovered electricity can be either used by the smelter or fed back to the grid

• Pressure regulation in gas mains
  

  We can recover wasted energy from reducing the pressure in gas pipelines

   

  • natural gas is transported long distances at high pressure.  When it reaches regional areas, the gas pressure has to be lowered.  The pressure is lowered again when before it reaches homes at a local station.  A GET can be used to recover the energy wasted in the pressure reduction.
  • Note, the gas will cool though the process so, it is necessary to pre-heat it before entering the turbine.

• Carbon sequestration / geothermal
  • Carbon dioxide that is captured from power stations can be compressed and injected into underground reservoirs.  Whilst being stored in the underground caverns the Carbon dioxide is heated by geothermal energy.  The heated carbon dioxide can be expanded through a GET and then re-injected into the reservoir.

Indirect Configuration:

The Green Energy Turbine can be used indirectly, for example as a part of an ORC process to capture waste heat.

In an indirect configuration the GET is used as part of a waste heat recovery system – for example an ORC (organic rankine cycle).  In such a system a refrigerant gas extracts heat from an object or medium which increases the temperature and pressure of the gas.  This pressurised gas is directed through a GET, which turns the turbine and results in lower temperature, lower pressure gas and electricity.

Some examples include:

• Biogas waste heat recovery
  

  Systems already exist for large Biogas producers, however Deprag’s GET helps small producers to recover energy

  • Deprag supplies low power (from 5kW) units to help smaller producers extract electricity from heat that would normally be wasted.

• Recovering heat out of industrial hot water
  • Deprag is supplying the GET to a company who can extract electricity from hot water.  Hot water is produced in various industrial processes, for example large ship engines, geothermal energy, solar energy and the power industry.  The potential for this already proven technology is enormous and game changing in the green energy and energy recovery industries.

Deprag’s Green Energy Turbine generator can be used in either a direct or an indirect configuration.

Direct Configuration:

Direct use of gas turbine generator for green energy

In a direct configuration a high pressure gas is run through the turbine. Electricity, lower pressure and lower temperature gas is the result.

Some examples include:

• Energy recovery in metal smelters
  

  Turn wasted hot compressed air into electricty

  • often molten metal is cooled by compressed air.  The compressed air flows through cooling tubes and is normally exhausted to the atmosphere.  The hot, compressed air can be run through the GET and the recovered electricity can be either used by the smelter or fed back to the grid

• Pressure regulation in gas mains
  

  We can recover wasted energy from reducing the pressure in gas pipelines

  • natural gas is transported long distances at high pressure.  When it reaches regional areas, the gas pressure has to be lowered.  The pressure is lowered again when before it reaches homes at a local station.  A GET can be used to recover the energy wasted in the pressure reduction.
  • Note, the gas will cool though the process so, it is necessary to pre-heat it before entering the turbine.

• Carbon sequestration / geothermal
  • Carbon dioxide that is captured from power stations can be compressed and injected into underground reservoirs.  Whilst being stored in the underground caverns the Carbon dioxide is heated by geothermal energy.  The heated carbon dioxide can be expanded through a GET and then re-injected into the reservoir.

Indirect Configuration:

The Green Energy Turbine can be used indirectly, for example as a part of an ORC process to capture waste heat.

In an indirect configuration the GET is used as part of a waste heat recovery system – for example an ORC (organic rankine cycle).  In such a system a refrigerant gas extracts heat from an object or medium which increases the temperature and pressure of the gas.  This pressurised gas is directed through a GET, which turns the turbine and results in lower temperature, lower pressure gas and electricity.

Some examples include:

• Biogas waste heat recovery
  

  Systems already exist for large Biogas producers, however Deprag’s GET helps small producers to recover energy

  • Deprag supplies low power (from 5kW) units to help smaller producers extract electricity from heat that would normally be wasted.

• Recovering heat out of industrial hot water
  • Deprag is supplying the GET to a company who can extract electricity from hot water.  Hot water is produced in various industrial processes, for example large ship engines, geothermal energy, solar energy and the power industry.  The potential for this already proven technology is enormous and game changing in the green energy and energy recovery industries.

Torque controlled screw tightening has always been the most reliable and easily applied method to produce a quality screw joint.  But is torque control really going to give the perfect assembly every time?

Torque curve based on a friction controlled screw joint

Firstly, what is a perfect screw joint? What do we want to achieve by assembling a screw in a product?

We normally need to join two parts together, but more than that we want to induce tension in the joint so that the parts do not come apart.  Sometimes we also need to seal the parts together to prevent leakage or keep dust and water out.

So the aim for a screw joint is not simply to assemble the screw to a target torque within a set tolerance, but it is to induce a constant clamping or pre-load force.

When we apply torque to a screw joint we can calculate the amount of tension induced in the joint assuming that there is no friction in the joint.  In a low friction assembly (eg machine thread screw into a pre-tapped hole) almost all of the torque will induce tension in the joint.  If you know the pitch of the thread and the torque applied you can then calculate the tension.

Fluctuating screw-in torque influences pre-load force!

What about thread forming and self tapping screws?  We know that a portion of the torque is lost to friction and by doing some analysis we can subtract the friction and figure out the average torque used to clamp the parts.  In most cases this will be enough, but what if the friction is not the same in every assembly?

What if a screw with a thread diameter at the high end of it’s tolerance meets a part with a hole dia that is at the low end of the tolerance?  In this case less torque will be used to clamp the joint and it may not be enough.  At the other end of the spectrum, there could be too much torque which could strip the joint or damage the part.

The solution is Friction Tightening.  The advent of EC and EC servo screwdrivers has paved the way to improving the quality of screw joints.  Today we can assemble the screw, calculate the friction torque and then add the pre-determined tightening torque.  So if the friction torque varies, the actual clamping torque and consequently the clamping force will still be constant on every assembly.

Using the friction torque measurement we cannot use the final torque for statistical analysis anymore.  The final tightening torque is the sum of the friction torque and the clamping torque the final torque accuracy will depend on the quality of the joint and the screws.  We now have to look at the clamping torque only for statistical analysis.

EC screwdriver controller AST40 and friction controlled torque curve

The friction torque method is already well established in the international automotive industry as well as the electronic, mobile technology, household goods and medical industries.

Friction tightening modules are optionally available on Deprag’s Hand Held programmable screwdrivers and machine mountable electric screwdrivers.

For more information or if you would like to discuss an application, please don’t hesitate to contact us.

Fully automated assembly systems not only offer fast assembly, but they also guarantee a higher level of quality control. Unfortunately, professionally designed, reliable automated assembly equipment is expensive and often inflexible. Unless there are very large volumes over a length of time, many automatic assembly automation projects are not viable.

The solution?  Intelligent – Manual – Assembly cells.

Increasingly manufacturers are finding a middle ground between hand assembly and fully automated assembly cells.  Unknown product life cycles, unpredictable demand and sudden downturns means that manufacturers are looking for the most flexible system possible.  With modern screwdriving, screwfeeders and controllers we able to guarantee complete process control, minimize assembly time and provide flexibility at the same time.

A typical Intelligent Manual Assembly Cell will consist of one or more hand guided screwdrivers mounted in a position control stand connected to one or more screw feeders.

• The screwdriver is typically freely programmable and different torques can be called up depending on the part to be assembled and the position of the screwdriver.
• The torque of each screw is monitored and recorded.  If a screw is not assembled to torque or depth the operator will be alerted.
• Screws can be automatically fed to the screwdriver after every assembly. We can even feed and assemble different screws for the one part.
• The torque, angle and assembly time of each screw can be monitored
• Other assembly tasks can be monitored by the controller and additional sensors
• The workstation can be designed for the assembly of numerous different parts

   

  

  Flexible screw assembly with full quality control

Peter Smith, production engineer at a well-known manufacturer of heating control units explained his requirements:

“Our heating control units are available, according to type and size of heating system, in the most varied of designs. With the recent introduction of our new control units we are starting three separate series, our HCU25, HCU50 and HCU100. When launching our new series onto the market we are unable to estimate the expected production amounts accurately. It is also difficult to plan out how the quantities required of each individual version will develop in relation to one other. It is for exactly this reason that we require highly flexible assembly equipment. Ideally production should be able to be simply, reliably and economically adapted to each of the product versions. Additionally for our HCU assembly we have the highest requirements for processing reliability as is usual for electronic components. The sequential order of assembly must be guaranteed and each step must be documented and integrated into our manufacturing execution systems”.

Normally this requirement of a strict sequence and documentation calls for automation.  However in the costs of automation and unknown production numbers excluded automation.

Deprag were able to offer an intelligent manual assembly cell that could be used to assemble all three HCU’s even though they each used different parts, sequence of assembly, different screws and torques.

Using interchangeable adapters, assembly can be easily converted to the various sizes of HCU25, HCU50 and HCU100. Work piece adapters are equipped with integrated sensor technology and communicate with a superior controller.

Furthermore the assembly required ESD safe and technical cleanliness.  The screws were fed with sword feeders instead of vibratory feeders and the assembly and positioning of the screws was done with vacuum pick up and particle killers.

Mr Smith says –

“The collaboration with DEPRAG has been impressive. All our technical requirements were realised with already existing harmonised standard components within the shortest space of time. And what is particularly important for us, all system components come to us from one source.  When we need to increase our production capacity we can flexibly expand our assembly line”.

If you would like to know more, or to discuss your project, please contact us here.

Almost every component of a product has a specification with an acceptable tolerance.  The component will have functional and physical attributes that can be measured and specified.  If the attributes are outside of the predetermined tolerance it will be rejected.

Screw joints are integral parts of any assembly.  Loose or stripped screws at best can cause annoying rattles and in a worst case they can cause complete failure of a product.  In any case, the long term costs of warranty repairs and harm to a brand will far outweigh the short term costs of correctly designing and specifying the torque, accuracy and type of screwdriving equipment for your assembly line.

Manual Screw Driving station with Automatic screw feeding and position control

Quite often we still find that many manufacturers do not have a torque specification for each of their screw assemblies, let alone calibrate their precision screwdriver or monitor their accuracy. Many screwdrivers in production have no torque control or are easily adjusted by the production line workers, while others are simply not checked until something goes wrong (oops too late!!).

“As long as the screw is not stripped”, “As long as a screw is there” are phrases our sales engineers often hear when they ask about the torque specifications. Unfortunately that is not good enough these days. There is no way of knowing if a screw is stripped after assembly unless there is some kind of supervision system or the operators care enough to reject the part as it happens. Just because an inspector sees that all of the screws are assembled does not mean that they are all assembled to torque or not stripped. Testing every screw after assembly with a torque wrench is a waste of time and inaccurate, especially when you can get screwdrivers that assemble screws more accurately than any subsequent testing method.

Customers expect more from Australian manufactured goods. You can imagine the disappointment of a customer who has chosen Australian made products and finds that it is faulty because of something as simple as a stripped or loose screw? He would probably think he may as well have bought the Chinese product for a fraction of the price. What if that company was one of your main export customers?

What’s the solution?

We recommend that manufacturers:

• Invest in torque analysis of their parts to first set a torque specification. The most basic requirement for any serious manufacturer who uses screws, should be to have torque specifications and a tolerance for every screw joint.
• Regularly check the calibration of the screwdrivers.  The Average and Standard Deviation of the measurements need to be checked.  The frequency of the checks depend on the quality of the screwdrivers and the importance of the screw joints.
• Only buy production quality screwdrivers. They are safer (quieter and more ergonomic), last longer and are more accurate than cheap drivers.
• Consider screwdrivers with supervisors to count the screws per part and check that torque has been reached on every screw.
• For complete quality control we can also supply Intelligent Manual Workstations where position controlled equipment monitors the position of the screwdriver and can even select different tightening strategies based on the screw position.
• If the joint is important, consider screwdrivers that measure and document the torque for each screw – don’t leave it up to the operator to tell you that there is a problem!!

How accurate do the screwdrivers need to be?

This depends on the tolerance that is required.  Generally industry expects a failure rate of better than 0.6 failures per million assemblies.  If the screwdriver is capable of a standard deviation (accuracy) of less than ±3% with a torque tolerance of ±10% of the target torque, then we can safely meet the failure rate of 0.6 per million.  If the screwdriver can achieve an SD of better than ±1% (for example our EC Servo Screwdrivers), then a tolerance of ±5% is possible.

Screwdriving Quality Control

We have over 20 years experience in helping customers with screw assembly productivity and quality control issues. Please don’t hesitate to contact us for advice on your applications.

Today we updated the Deprag Advanced Line air motor catalogue. A few new high speed 20W and 30W motors as well as a lower speed 80W motor were added to the range.

Our Advanced Line of air motors has to be the most comprehensive range of low power motors on the market!

All Advanced Line pneumatic motors are fully sealed, have stainless steel bodies & spindles and most are ATEX approved for use in hazardous areas.

Click here for more information on high torque air motors and to download the catalogue.

We have just updated the prices for our underground ready impact wrenches.  We know that the prices of our smaller tools are much higher than the “throw away” plastic tools that are on the market, but these are obviously not throw away tools.

The zinc alloy bodies guarantee a rugged, heavy duty, spark free tool with the peace of mind of having an ATEX approval to back you up, not just an “underground ready” statement.

In the long term our Deprag impact wrenches will save you money.

See the underground impact wrenches here

Welcome to the Assembly Technologies P/L blog.

We are the Australian representatives for Deprag and Cengar products and commenced business in October 2006.  Deprag and Cengar are both small enough to be flexible and react to special requests as well as large enough to be competitive and to keep at the forefront of innovation in their fields.

Our Manager, Paul De Rossi has been product manager for Deprag and Cengar products since 1992 guaranteeing you expert product advise and service.

We look forward to keeping you up to date with new and interesting products and solutions through this blog.  We welcome any questions or criticisms, so please let us know what you think.