|Abssac Newsletter : April 2014|
As the name suggests, we supply a spring that is machined from a single piece of material. This also includes the end attachment features.
The most demanding extension, compression, torsion, and lateral bending and translation spring applications can benefit from machined springs because of their superior function and inherent versatility.
In this issue of our Newsletter we look at our MACHINED TORSION SPRINGS.
For those engineers familiar with the traditional wound spring format we are offering a new way of looking at both performance and attachment. Machined springs deliver enhanced functionality, increased precision and cost reduction as a result of true engineering expertise.
It really is worth
We like to think of it as ....Precision Elasticity...
The most common machined torsion spring configuration is the single start spring, which consists of a single continuous coil element, which starts at one end and terminates at the other end, much like its wire wound counterpart. We can supply both unwind and wind up torsion springs and in both cases the spring rates achieved are as linear as the geometry will permit.
However, it is not only the accuracy of rate which is an advantage, since the part is machined, we can incorporate any form of end attachment into the torsion spring. It is therefore important to remember that we can supply an attachment integral to the machined spring that allows the PURE MOMENT to be resolved.
In the wound torsion spring format, tangs are produced by bending the last portion of wire into a set position. These tangs are bent inward or outward upon which a force can be applied. This not only limits the actual attachment designs available but induces high stress into this attachment area.
In the machined torsion spring the tang is integral and without stress making it a far more rugged and reliable attachment. Tang usage is designed to provide a moment on a torsion spring. To accomplish this, a force at a distance is employed. The spring provides the moment reaction, but there needs to be an additional reaction to the force.
Typically with wound springs, using a tang, they are called upon to resolve this force by the ID or OD of the spring rubbing on a guide.
Uniquely, with a machined torsion spring, the application of a moment is possible using a pure couple design.
It is also possible to resolve the moment by an integral torque restraint on the coil side. How you attach the machined torsion spring is often up to your imagination, perhaps incorporating additional parts of the system into the single spring system.! However it is important to remember that the full breadth of machined attachments that resolve a PURE MOMENT are available to you.
Give Chris a call to discuss further
The stress found in machined torsion springs is dominantly a pure bending stress providing a more reliable and accurate part because virtually all-residual stresses are eliminated during manufacture. By predicting the torsion rate via finite element analysis, we can easily achieve 10% on rate and can be tuned to +/-2% for the more demanding applications.
Precision miniature motion designs
Cold rolled formed lead screws are a superb economical solution for linear applications requiring repeatable accuracy and reliability. Using a comprehensive range of screw diameters from 3mm through to 24mm, Abssac can match performance and function by offering the capability to supply custom thread forms and nut designs.
Whether it is a fine or coarse pitch thread, the end result is a high integrity lead screw and nut product that is ready to be fitted directly into the application and perform.
Phil Jones at Abssac states “We like to pride ourselves at Abssac on our excellent product knowledge for precision miniature motion designs, which are not only excellent quality but also competitively priced”.
Tel: 01386 421005
Great Value its Groovy….. 30% less cost. Low cost motor shaft couplings
Abssac announces a 30% reduction in the price of its MC series motor couplings for 2014. Available in Aluminium and Stainless steel as standard, the MC series delivers zero backlash constant velocity connection between shafts.
Lead screws supplied in both a right handed and left handed thread format can readily be supplied by Abssac limited. A redesigned food packaging machine was originally using the opposing screws to operate a high speed gripper in a machine that hot plastic foil sealed, ready to cook meals for a leading supermarket. Since the machine operated within a food grade environment meant there could be no lubrication with the system, which contributed to the premature failure of the nuts after only 50,000 cycles. It was also a concern that the existing lead accuracy matching between leadscrews could also be a factor in the excessive wear of the nuts.
By utilizing a PTFE impregnated plastic as the antibacklash nut base material and ensuring matched pitch accuracy of the screws in both the right handed and the left handed screws enabled initial tests cycles up to 56,000 cycles to be completed without any sign of wear to the nuts.
Mr Phil Jones of Abssac says” By being able to match the screws pitch accuracy reduces the stresses within the system considerably ensuring a more reliable linear movement”
Ideal for electric motor, servomotor drives the single piece construction allows constant velocity and high torsional stiffness.
Fixing the shaft coupling to the shaft could not be easier thanks to the unique integral clamping design of set screw attachment. The MC series caters for shaft diameter from 6mm to 30mm . The MC series can also be supplied with key ways.
Electrodeposited products are formed by machining a precision mandrel to the shape of the desired form and then depositing the correct thickness of quality metal on to the mandrel. The mandrel is then dissolved away leaving the precision finished product behind.
This same process can be utilised using gold, which allows the remarkable properties of the material to be exploited.
Gold is the most non-reactive of all metals. It is benign in all natural and industrial environments. Gold does not react with oxygen, which means it will not oxidize or tarnish. Gold is among the most electrically conductive of all metals and is able to convey even a tiny electrical current in temperatures varying from -55° to +200° centigrade. Gold is also the most reflective and least
absorptive material of infrared (or heat) energy. High purity gold reflects up to 99% of infrared rays but is it also an excellent conductor of thermal energy or heat. Lastly, Gold is ideal for invasive or implantable medical devices as it is one of the least rejected materials in the human body.
This unique combination of properties makes gold a vital component in many medical, industrial, and electrical applications.
By refining the gold electroforming technique we can supply extremely intricate parts with unusual shapes, thin walls, deep crevices and other design features. The electroforming process is especially crafted for tolerance-critical miniature parts and makes them suitable for both flexible bellows and rigid electroformed components.
The controlled electroforming process can also vary the wall thickness in different places on the same part for selective rigidity and flexibility allowing hollow parts with walls as thin as 0.0005” [0.012 mm] for miniature applications including electrical bellows contacts and precision instrument applications.
ETP Hub Shaft
ETP Hub Shaft connections improves productivity in rotary PET bottle stretch blow moulding machine
The ETP shaft connection solution is designed to allow the user to tighten or loose a single cap screw to allow the quick and easy
mounting and dismantling and if necessary
An excellent example of this products placement is in the production of PET bottles. This highly competitive business uses the stretch blow moulding process, which depending on the type of machine can have from 4 up to 36 blow moulds per machine; thus the output of the machine can range from 8,000 up to 72,000 bottles per hour.
Preforms of the bottles are inserted into the blow moulding machine via a conveying system. The machine consists of a linear
heating module for preform heating and a blow-moulding module in which the heated preforms are blow-moulded into bottles. The preforms initially pass through the heater to achieve elasticity. Next step is the transfer of the preforms into the blow moulds. To fasten and centre the transfer wheel an ETP-EXPRESS is used. The single screw design enables quick and easy mounting and adjustment which is a key benefit.
The rotary blow mould machines are often recognised within the filling and packaging industry for their unmatched efficiency, and in ey applications ETP is increasingly forming an important part of the design.
Have you heard?
The low friction within ball screw designs means that a high mechanical efficiency is delivered compared to that of lead screw designs. A typical ball screw may be 90 percent efficient, versus 50 percent efficiency of a lead screw of equal size. Ball screw specification is often a result of an applications requirement to have smooth, accurate and repeatable linear movement.
A recent application for Abssac specified a precision ball screw within an electronic microscope that placed a precision guillotine against test pharmaceutical materials. Extremely fine slithers of test material are then cut off the material in rapid succession for microscopic investigation. A small variance in the sliced materials overall thickness would have had a detrimental effect on the accuracy of the microscopes results. The application demanded a high degree of repeatable accuracy and a precision ball screw could also
satisfy the other design prerequisites for it to be compact, quiet and cost effective.
By using precision ground ball nuts and then pairing them with precision cold rolled ball screw threads, Abssac could provide a ball screw with lead accuracies of less than 52 microns of error for 300mm of linear travel. By utilizing both ground nuts and rolled screws formats enabled large cost savings, when compared against a completely ground ball screw equivalent.
Abssac has well over 30 years of experience in supplying precision ball screws. Typically, precision ball screws with outside diameters in the range from 1.8mm to 20mm with a range of leads per diameter can be supplied. Abssac’s ball screw customers often request that the journal ends of the screws are supplied pre-machined, so that the parts are ready to fit. This eliminates potential scrap
rates for the customer but also ensures that the assemblies are supplied and certified to the accuracy tolerances required.
Mr. Phil Jones at Abssac Limited says, “The precision miniature ball screw ranges we supply are ideally suited to optical devices or miniaturized positioning equipment. As manufacturing designs get smaller and demand for more accuracy increases, we can now offer a way of supplying what the designer has previously not been able to obtain.”
Why not give Phil a call to discuss where this product can help you 01386 421005
Schmidt Offset Couplings aid in the manufacture Gold Fever of wind turbine blades
Used to drive the rubber pull rollers and heated laminating ollers that create a structural adhesive for the manufacture of pre-impregnated composite fibes. During the manufacture of the wind turbine blades, the parallel distance between the driven rollers and motor to be constantly adapted to the changing thickness of material substrate. The Schmidt Coupling allows this dynamic ofset whilst maintaining constant velocity torque transmission.
Get a grip……Ground ball screw
When Abssac was confronted with this exact set up within a confectionary machine the solution was to use a standard range of ball screws manufactured exactly for this purpose. Abssac supplied a ground 12mm diameter by 2mm lead ball screw in both a right hand and left hand format on the single screw. In affect both screw thread forms met at the centre of the screw, separated by a small blank section. This enabled two nuts to then be mounted on the screw which would then move in opposition to each other for a single screw direction of rotation. Therefore a pinching or extension movement could be achieved with the opposing nuts with up to 5 micron accuracy.
From this application a further 4mm, 5mm, 6mm, 8mm & 12mm diameter screw series have been developed utilizing 1mm to 5mm lead options. Matching the bi-directional requirement with high end repeatable accuracy was another design solution supplied by Abssac.
Using 316L stainless steel Abssac has recently supplied a set of self-reversing screw and follower nut for a custom marine subsea application. The self-reversing screw product does not require the driven screw to change its direction of rotation to enable the nut to return to its original start position.
The reciprocated bidirectional movement is achieved by using a follower blade in the nut, which is matched to the particular groove width and screw turn round on the screw.
On time and on budget.
Abssac delivers 2000+ Stainless Steel nuts for a lead screw
Abssac sponsors EHS Robotics Club.
Abssac is proud to announce the sponsorship of the EHS Robotics Club, who are keen to enter the VEX Robotics competition. The Evesham High School Robotics Club consists of three teams: Tolerance, Titan and Tangent and we wish them success in this years competition.
For further details look at the web site http://ehsrobotics.co.uk/