"My labels are sort of wrinkling."
I'd been ho-humming it reading through the latest Packaging Digest and when Ralph told me this, it got my attention.
" 'Sort of wrinkling'?", I asked, "I'm sort of curious what that means."
" I don't exactly know, " Ralph confessed. "Some of them just look funky. I need you to come here and take a looksee."
When I saw his capper I suspicioned what the problem might be. When I saw it run, my suspicion was confirmed. The cap chuck used a tapered rubber friction insert.
"Fiddlesticks on funky labels," I told him. "Your problem is bent bottles."
"This type of capper needs downforce to get sufficient friction between cap and chuck. Your bottle is not strong enough to withstand the downforce and is deforming. As the cap tightens, a slight internal vacuum is locked in, preventing the bottle from regaining its original shape.
"It doesn't look like much but it is enough to prevent the label from applying properly. Since the deformation is not consistent, there is no way to compensate for it. "
Stronger bottles are a solution but that's not gonna happen. A different style chuck with more positive grip will also help. The best solution here is to add a neck support ring to the starwheel. This prevents any downforce from being transmitted to the bottle.
Don't let bent bottles get you down. More importantly, don't let down get you bent bottles.