That’s a good question.
We incorporate cooling tray covers because our cooling trays are very much higher performance than industry standard. They are designed to cool a full batch of coffee from second crack within 4 minutes and they are designed to accommodate 3 full batch sizes for blending roasted coffee.
That means we use very powerful stirring arm motors that find limbs to be of minimal impediment.
Beyond that, we build professional commercial production equipment that is not infrequently operated by people that have never had the benefit of basic machine safety instruction. Stuff like don’t let long hair, loose clothes, or poorly considered jewelry drag you into the rotating parts of a machine.
I know of three cases where people suffered grievous bodily injury from their roasters. One man slipped in front of his 5kg Probat and ended up loosing several fingers to his spinning drum. Another lost a hand on the drive chain of a San Fran roaster. We had a young lady snag an oversize stainless steel medical bracelet on the stirring arms of a 6kg roaster and nearly lost an arm.
All freak accidents, but once was enough. An ounce of prevention is worth a pound of cure.
Just to illustrate how backwards our industry can be, up until recently (and almost 80 years after the development of PTFE) manufacturers were still using stainless steel brushes in their cooling trays and about 40% of professional roaster operators had scarred up right hands from getting their hands caught under those brushes while grooming the roast mid-cycle.
It’s just coffee. It’s not worthy of ritual scarification or blood sacrifice.
By the way, those aren’t “dumb” covers. Our cooling tray covers are incorporated into the machine control system in a way that automatically starts the stirring arms and cooling fan at the end of the roast, halts the arms when the cover is opened, and turns off the fan when the coffee is discharged.
This highly useful “operator assist” automation relieves some of the tedium of production roasting. It’s also part of a signal to the control system that triggers the machine to the original charge state parameters (temp, air flow, drum speed, fuel) for automated precision between batch protocol.
We’re probably better at building machines than “selling” them and a lot of what we do isn’t exactly obvious from the pictures. Thank you for taking the time to ask.