Norlok Clinching Machines
Fastening ductwork like square to rounds and flex connections into an assembled fitting can be done with drill screws, pop rivets, an Acme lock, a spot welder, or a clinching machine.
Pop rivets and the Acme lock (run outboard of a Model 20 Pittsburgh machine) are still widely used in many duct shops for fastening, but each is costly in its own way—and labor-intensive.
In mid-sized to larger shops, spot welders are much more common.
While a spot weld's burn marks don't make for an aesthetically pleasing product, the products made in a duct shop typically don't require it.
One reality many shops are facing is that their spot welder is very old and needs to be replaced. Most of the leading manufacturers of spot welders over 20 years ago—LORS, Micro, Peer, and Western Arctronics—closed their doors several years ago; parts for their machines are increasingly a challenge to find.
We've seen a trend in HVAC duct fabrication shops of replacing old spot welders with free-standing C-frame clinching machines instead of another spot welder. These are pneumatic machines with a rounded design punch that descends from the upper tooling and squeezes together two layers of metal that are resting on the die. The result is a clinch joint that is stronger than the metal itself.
Shops with a clinching machine have found that they can make square to round, drain pans, flex connectors, and other fittings much faster than they could with their spot welder while also improving the appearance of their fabricated product.
The two main sellers for us in the duct fabrication space have been the Norlok Surelok models SLII and SLIII. Both have the exact same capacities (2 pieces, 30 gauge to 14 gauge) and clinches per minute (60 to 80). Under normal operation, both punch and die last for approximately 250,000 cycles (clinches).
There are some differences between the two models that are worth considering when determining the best value for a specific shop and whether to spend the additional $8,000 for the SLIII.
1. Air Consumption:
The SLII and SLIII have different power sources that make for a big difference in the amount of air required for each. The SLII runs off a WAMP-style unit; the SLIII runs off an "Advanced Power Unit" that requires a smaller diameter air cylinder pneumatic power source for the clinching stroke and ends up using one-third less air than the SLII. When the compressor is turning on less frequently, the shop's power bill will be less each month. In short, the SLIII's energy efficiency is the most significant difference.
2. C-Frame Opening:
The distance between the front lower and upper arm on an SLIII is 12"; on the SLII it's 5-1/2". One of the main design features of the SLII is the five-inch opening in the C-frame that keeps the alignment extremely true over time. Even machines from the 1980s have this reliability in the frame and are still working just as they did when new. When designing the SLIII, Norlok did a lot of analysis with simulation software data to give as much access at the front (where most of the clinching happens) but still allowing some room at the back, keeping the same strength that the SLII enjoys—even with a wider opening. This larger opening makes the SLIII more versatile when doing flanged or larger pieces, without sacrificing alignment.
3. Distance Between Punch and Die in Open Position:
The SLII has a distance of 1" between the punch and die; the SLIII has a 2-1/2" distance.
4. Speed:
Though both machines operate at 60-80 cycles per minute, the SLII is only operating with a 1" stroke, and the SLIII has a 2-1/2" stroke at that cycle speed, thereby moving at a faster speed. By reducing the stroke (tooling open height) from 2-1/2" to 1", the clinches per minute can be increased to 120.
Other differences that are less significant but worth mentioning:
Stainless Option: Clinching stainless isn't easy. Stainless is a very hard metal, and with round tooling it's a challenge to generate enough power to coin the material at the bottom of the pocket. Though many shops use the SLII and SLIII for occasional clinching of two pieces of 26 ga stainless, for anything heavier or frequent, this is not advised. The SLIII has the option of changing out the round standard tooling with a rectangular tooling kit for fastening stainless steel. By changing out a set screw on the bottom that holds the die in place and a small set screw on the top that holds the punch in place, it can be changed over in a matter of seconds.
Laser Light Assembly: Standard on the SLIII and an option on the SLII. This laser is simply a marker, useful for the operator to know exactly where the clinch is going. On the SLIII there's more distance (2-1/2") between punch and die in open position than the SLII (1"), and thus proves to be more useful.
SLIII comes with choice of 3 Dies, SLII comes with 1 Die:
When a shop buys an SLIII, they get one die mounted on the machine plus two extra dies included. With the SLII, just the die that comes with the machine is included. #30 Yellow Die for 30-24 gauge, #40 Blue for 24-20 gauge, #50 Red for 20 through 14 gauge. The same punch works on all gauges. The dies for an SLII and SLIII are not the same.
Safety Feature is Standard for Both SLII and SLIII:
One area that Norlok makes equal is when it comes to operator safety. No matter the model, when the tooling comes down, it does so under a low-pressure approach stroke until it reaches 3/16" of an inch. As long as the two pieces of material are within 3/16" of an inch of each other, the high pressure fires and the material is clinched together. If the two pieces are not, the tooling is going to come down but it will not reach the high-pressure point at 3/16". It'll just pop back up and return to the raised position without clinching. That 3/16" is set so that if an operator accidentally leaves a finger in there, the machines are not going to fire (it’ll make a little pinch, but it won't fire).
Summary:
In duct shops most of the attention goes towards the machines instrumental in efficient shop flow for making straight duct and fittings. If one of the machines used in this shop flow goes down (the plasma table or the Pittsburgh machine, for example), there's often not a backup means of doing what that machine does. In fastening, there's always an alternative—spot weld, pop rivet, Acme lock, even drill screws—and that tends to deem it a less vital role in the shop's ability to fabricate rectangular straight duct and fittings.