For those of you who didn’t receive the November issue of Canadian Industrial magazine (CIM), I was interviewed for an article on shearing and it’s place in Canadian manufacturing today.
Below you can read the entire article or it can be viewed as it appeared in the CIM magazine, I hope you find it informative.
CIM: How has shearing technology changed recently?
McLean: If any area has changed in shearing, it is in the area of controls.
Most manufacturers either use third-party controls or they manufacturer their own, and as long as they control blade gap, rake angle, and backgauge positioning, they pretty much have all the necessary makings of a good control. With shear controls, simple is always better.
CIM: What specifically has changed because of this control technology?
McLean: While shearing controls have vastly improved, the principle of shearing has not. Blade gap control, rake angle, and backgauge positioning are essentially the only three variables in shearing, and any improvements will come from NC and CNC, along with motion control.
CIM: Is there still a role for shears without an advanced control option?
McLean: You will find that with most shear manufacturers today, the bare minimum control is a digital readout with forward and reverse push buttons.
With the cost of labor today, and the lost productivity that comes along with a manual shear, it is my opinion that the role of shears that are not NC or CNC will become less and less. This is primarily for shears that are 10 ft. and larger. For most sheet metal shops using 4- and 6-ft. shears, manual backgauges are still the norm.
CIM: What sets one shear apart from another?
McLean: There are primarily two styles of shears: swing-beam and guillotine.
The swing-beam shear is a tried-and-true shear that has been around for many years. It is the less expensive of the two because its design has a blade that pivots on a fixed bearing. The guillotine shear, which tends to be more expensive, has a moving blade that runs up and down in straight slides or gibs. The upper or moving blade is parallel to the lower, fixed blade during the entire stroke.
The swing-beam shear also has a fixed rake and an adjustable blade gap, whereas the guillotine shear has the ability to adjust the rake angle and blade gap, resulting in less twist, camber, and bow in the part.
CIM: How can a shop select which shear best suits its needs?
McLean: Swing-beam shears are ideal for most general fab shops, but if narrow strips are the majority of what is being cut, then the guillotine shear is a better choice. When cutting narrow strips of metal, whether it’s plate steel or sheet metal, the control of the rake angle of the blades is critical to both good edge quality and a straight part.
CIM: Why do shears still have a role in today’s shops?
McLean: The majority of fab shops still have a shear of some sort. A shear is simple and cost-effective so, in my opinion, shears are here to stay and will always play a role in Canadian manufacturing. Undoubtedly, the shear can cut simple square or rectangular parts faster than laser or plasma cutters.
Training a shear operator is also much less involved than training a laser or plasma table operator. We are finding many shops that have lasers and plasmas that initially thought they would use them for all their cutting needs, but now realize that it is more cost-effective to cut the simpler parts on a shear.
CIM: Can shops prevent the shear from becoming a bottleneck?
McLean: In shops where there is only one shear and bottlenecks are happening, they can be eliminated by purchasing a 4-ft., 14-ga. or 10-ga. hydraulic shear to use for cutting smaller-run jobs or parts. If shops are losing an hour or more a day in productivity, it only takes simple mathematics to figure out that the payback on a $6,000 to $8,000 piece of equipment would not be long.
CIM: How can shops speed up the shearing operation?
McLean: An option on Durma’s 10-ft. by 1/4-in. shears uses hydraulic power on the downstroke, but the return of the blade to the top of the stroke is done by means of a nitrogen-charged canister that greatly reduces the time it takes the blade to return to its home position.
In comparison, most conventional hydraulic shears have double-acting hydraulic systems where the blade is slow going down and slow coming up as well.
CIM: Can accessories improve the process?
McLean: There are many options like sheet support systems that eliminate the need for a second operator to stand at the back of the shear to hold lighter-gauge material up against the backgauge to prevent the material from drooping.
Also, a conveyor/stacker unit can be added to the back of shears. The conveyor moves the material either down into a stacking unit or, in some cases, returns the plate after it has been sheared back to the front of the shear.
A scrap separator unit can also be used to separate the trim cut or scrap material from the usable material.
With the advancements in control technology, backgauge speeds and accuracy have vastly improved over the past few years. When coupled with ball-screw and servo drives, the shear becomes a valuable, cost-effective way to part metal.
One other item that is not really talked about much is laser line cutting. In the past most shears have had what is called shadow line cutting. Today we are seeing many shears with a bright red laser line that shines at the cut line to make it easy for the operator to place the sheet in line with the mark on the sheet or a scribe line.
CIM: Are these options mainly for safety or for processing capability?
McLean: As long as the finger guarding is in its proper place, and the back of the shear has guarding to keep bodies out while the shear is in operation, the shear is considered fairly safe to operate. Any of the previously mentioned options would be purely for increased productivity.
CIM: How can shears be operated in a manner that is safe for the operator and productive for the shop?
McLean: Shears, like any piece of production equipment, must be maintained and fine-tuned as they wear. Proper finger protection is the No. 1 safety feature on any shear that will save the operator from bodily harm, not only from the blades themselves, but from the hold-downs as well.
The key to safety is proper height adjustment of the finger guard, proper lighting shining down on the blade to ensure the operator can see the shadow line and the scribe marks on the material being cut, and interlocked guarding or safety lights for the back of the shear to keep people and property safe.