Curing Stations, Drying Time, and Workflow

      A small ultraviolet or infrared curing station might speed up a small finish line's production. Here, finishers talk about equipment, formulas, drying times, and efficiency. May 17, 2005

Question
I have a small shop with two men doing all of the finishing. The finishing seems to be the constant bottleneck. Is there some kind of infrared drying system that would be beneficial for a small shop? I have seen the big ones that are used in high production. Then there are little ones that are more geared to the auto shops. Does anybody make an infrared oven kind of like a roll-through pizza oven? My finishing building is only 1200sf, so it could not be too large. I can't believe that with all of the woodworking machinery marketing that gets thrown at us, someone is not being a little more creative in solving the finishing problems in small shops. If there is a solution out there, someone needs to get their marketing department into gear because I have been searching for months with no results.

Forum Responses
(Finishing Forum)
From contributor M:
There are some UV tunnels, and UV cured finishes. This might lead to some better ideas.



From contributor B:
I gather you are using waterborne products for your topcoats?


From the original questioner:
I am using solvent based sealer and topcoat. I have seen the infrared dryers used in a big cabinet factory that was using post cat lacquer but that was part of a $2 million finishing line.

I will have to do some research into the UV coatings. I have seen those units on Ex-Factory as well. I think those were primarily set up to do roll coating and curing of sheet stock like plywood.



From contributor A:
There is a system called Prime Heat. I investigated for our company (7 in production, 1 full time finisher; 50% clear stain, 50% pigmented finishes). The investment was approximately $15,000 for us.


From contributor J:
I have two rolling UV heat lamps that look like fluorescent fixtures and I can't see any use in this type of system unless you pour big money into an oven or a turnkey operation. With two guys in the shop for finishing, there should be no bottleneck. Temporary sanders and helpers can ease the strain, but maybe it is the finishers and not a question of new equipment. If you speed up the drying, all you will have are dry cabinets left waiting around in the bottleneck! I use the contractor site heaters to expedite matters in the winter time, but there is always something that can be done while waiting for finish to dry like taping/papering, cleaning spray equipment or getting the stains or toners ready to go. Just seems you might do well to check on the efficiency.


From contributor C:
How many cabinetmakers are feeding the two finishers? I don't use wb, but in my shop, the drying isn't where the bottleneck occurs. It's fixing defects and scratches. The most time consuming aspect of my usual finishing schedule is staining and sealer sanding. I have a total of about 600 sq ft for my finishing area and for the drying/holding area for completed pieces. I think you need to evaluate your processes and see what needs to be rearranged. Normally I have no problem as the single finisher with a dozen cabinetmakers feeding me work. At the times when a job is more time intensive, I let the boss know and he has someone sealer sand for me so I can press on with spraying. Bottlenecks happen but can be alleviated through observation and corrective measures. Obviously, you're looking at this and thinking that speeding up the drying time will fix the bottleneck. Just make sure that's where the true bottleneck is before investing money in a fix that may not be needed.


From contributor C:
I use SW precat, which has a 15 minute dry time, so by the time I finish shooting a rack, it's dry enough to start sanding the ones first sprayed. Topcoat drying times are obviously longer, needing an hour to dry enough to handle (gently) and 4 hours to be dry enough to pack up.

So here is my time schedule for doing a rack of 50 raised panel cabinet doors with a clear coat finish:
20 minutes to seal the face and edges.
20 minutes to seal the backs.
3-4 hours to putty nail holes, sand out glue spots and sealer sand.
30 minutes to topcoat the back and edges.

Clean gun, clean up overspray from floor and stands. Follow up with team leaders for jobs coming my way and empty dried racks to make room for more in-coming. By that time, an hour has passed and I can shoot the faces without marring the finish on the backs. 30-40 minutes to topcoat the faces. Then a four hour drying time before the cabinetmakers can touch them.

For 50 average sized raised panel clear coated cabinet doors, that is a total of 10.33 hours from the time I first start working them until the cabinetmakers can punch and install hinges. I always finish cabinet parts first so the cabinetmakers can stay busy assembling while I'm finishing the more time consuming doors and drawer faces.

It's all about a smooth process flow and knowing how many man hours each process takes. Once you've got that down, adjustment to variations is easy. If I'm working multiple jobs, a single cabinetmaker can make the doors needed to keep me shooting. If that is the only job I'm doing, though, a single cabinetmaker can't build doors fast enough to keep up with me finishing them. So where is the bottleneck there? Not in my finishing room.



From contributor O:
The drying time of lacquer and pre-cat lacquer is not dramatically changed by heating it. Prime Heat is good, as it uses halogen lights to heat it, but with pre-cat lacquer you have to let it flash off before you put it under the lights or it can blister. Then you put it in there for 15 minutes and you have to wait 1 hour after that before you can sand and 4 hours before you can safely turn them over. I think it is overrated. The best finish for using heat is CV, but many people shy away from that because it is a different technique to spray it. You can bake it 30 minutes almost right after you spray and it dries enough to turn it over in an hour.


From the original questioner:
Contributor A, I would be very interested in what products you use and what finishing schedule you follow. Do you have to flash off before you cure or does the unit do both? Is it a roll-through flatline type?


From contributor A:
I apologize for not being clear in my first post. I do not have the Prime Heat system set up in my shop. We investigated it but have not set it up. We spray both pre-cat lacquers and CV and are now looking into a very new product out of Italy - a catalyzed urethane made by a company called Milesi. It is distributed through Chemcraft. I want to try this product before investing in the Prime Heat. Anyway, I have one finisher and six people in production. We outsource all of our doors, drawer fronts and all mouldings, which means that at times our finisher can be pretty well overwhelmed with the volume of product to spray. If a new product or the Prime Heat system will allow me to avoid hiring another employee to assist my finisher, then the investment pays for itself very quickly. In any case, we have decided to try this new product first and then reevaluate the Prime Heat at a later date.


From contributor B:
Contributor C, as I understand what you wrote regarding shooting SW's pre-cat, you can shoot the backs with the lac and in about an hour (?) you can turn over and do fronts. In 4 hours, your assemblers can start putting everything together. Is this what you are saying? I may not be reading this right, just want to be clear on this. Do you not have marking on backs when you leave them on the racks for 4 hours? Also, how about your system time for doing pigmented lacquers on doors?


From contributor C:
Yes, after shooting the backs with SW precat, 1 hour of drying time is all that is needed to be able to flip the doors over and shoot the fronts without any marring occurring to the backs. With heavier pieces such as an applied bulkhead for a refrigerator, I give it a bit more drying time. But for standard cabinet doors, 1 hour is all that is needed for the finish to dry enough so that the weight of the doors will not cause an indentation. I haven't done any pigmented lacquers, so I can't say.


From contributor T:
We are finishing wood products with water based coatings, so our application is quite different, but we've just returned from testing at CCI Thermal Technologies. So far, they've been very helpful and accommodating and we haven't even bought anything, yet.

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