Barry, thanks for the help. We have basic issue sliding bed conveyors with worm gear drives. The environment is pretty humid, but not wet like washdown conveyors.
Steel rolled and aluminum frames are too light construction for heavy duty. That motor frame and motor will last a few years. Cast Iron frames are the best option.
With what you are doing I would go with the aluminum frame.
The motor should not be subjected to any major impacts during it’s life where it is mounted. Aluminum holds up better in most humid places.
A worm gear produces a lot of heat while running. In a 50:1 worm 50% of your power is used up destroying the bronze gear. Cast iron has a thermal conductivity of around 20 btu/hr-ft/F while the cast aluminum will be around 100 btu/hr-ft/F. While the cast iron frame will be larger, once you have reached a steady state with fan cooling the aluminum frame will be as cool or cooler unless you are talking about mill duty motors.
I would also look into getting a gearbox with an integral motor to save money, maybe $30 a unit. The user should not mind if is willing to buy a worm box.
Both the cast iron and aluminum will be over 30,000 tensile but the cast will be thicker.
The rolled frame would probably out last the box but the heat would reduce the L-10 life of front bearing. It should still make it through a 2 year warranty at a high enough percentage to save money. Remember that a lot of times when something fails after a year it will never be returned for warranty. The maintenance guy will just change it out with a spare and no one will know. This is particularly true with motors 5hp and under.
Barry, I can tell you've done this before. What's the differnce between L-10 and B-10 bearing life? Also, thinking about the integral construction with a helical bevel box (better efficiency, lower heat, slightly more cost). And even thinking about NEMA premium, if the motor lasts long enough to pay off with energy savings.
The best gearbox for the customer would probably be a Stober. They are probably the best engineered boxes in the world, are assembled in Ky. and have 24hr service. There are some companies, like Anheuser-Busch, who are replacing good SEW’s and Nords with Stober because their maintenance software proves they save a lot of money by doing it. The problem is they cost about 10% more than SEW or Nord and a whole lot more than a worm box.
On the side, the things that fail first on a bevel or good hypoid box will be the input pinion seal or bearing. Stober has designed their input pinion to reduce the OD of sealing surface and have two pre-loaded bearings on input. They also precision grind their output shaft which seems a bit anal to me. Stober also does not make an integral gear motor because they know the first thing to fail will probably be the motor.
Brother probably has the best gearbox for the money in the 1/50th to 3hp range. They are very efficient, all position mounting, no vent, 100% thru hardened gears and offer 56C and integral gear motor. They are very well designed and are used in a lot of high reduction and true 24 hour applications like mixers for slushy drinks. They are made in Japan and take 3 weeks by air or 6 weeks by sea. So unless you have some volume forget them.
SEW and Nord both make very good gearboxes and fair integral gear motors. Avoid the SEW integral if you are using a VFD and 460V. SEW came out with the “Spiroplan” to try to compete with Brother, it is an all steel worm gear and is crap. SEW also came out with a new keyless hollow bore clamping arraignment which is crap.
Falk-David Brown-Textron have a nice little helical worm box that has a 5:1 worm and a helical first stage. The bronze gear is still a wear item but they are fairly efficient and last much longer than a single stage worm. This might be a good middle ground between quality and initial cost. Stober also makes helical worms but the added cost would probably not be worth it since you still got the bronze gear.
If you are going to use a premium efficient motor check the torque curve to make sure it is a good fit for your application. Some of them have a lower starting torque.
Probably the best way to improve the design for cost cutting, quality improvement or both is to learn more about your product. If you set up a test conveyor with a torque arm mounted gear motor to measure actual torque you might be surprised at what you learn. Sometimes little things like the position of the nip roll can make a big difference in cold weather. Some belt manufacturers have classes and test conveyors already set up. You can also talk to the maintenance people to find what breaks first.
This reply has gone on too long. I guess the most important thing to remember is to use the cheapest piece of crap that has a chance to make it through warranty. You might even go with B-15 or B-20. Your salesman is not going to be able to sell the improvement in quality because he can’t explain it and is not talking to someone who would understand it. He already says your stuff is great just like the competition does.
How much does it cost and what is the warranty? The rest is yatter.
