stainless dome head bolts

[jlnsol]

Who knows a source for stainless dome head bolts (metric)?
It is the type of hexagonal head bolt with rounded head above the heads' flats. They seem to be used in industrial and farming equipment. Want to use these ase hygienic fastening solution in food-machinery. Eventuelly a flange at the bottom of the head is OK but not a must.

 

[prex]

You have hexagonal blind nuts with spherical cap, but I'm not aware of hexagonal head screws with spherical cap. Or you can have various types of cupped or button head screws.

prex
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[Screwman1]

Call Infastech or ATF. They could make some for you. I doubt that you will find these off the shelf.

 

[btrueblood]

Sounds like you want a carriage bolt (except those have square faces below the dome, not hexagonal)? Lots of places offer those, but I can only find them in inch sizes, not metric. Similar, but unlikely to be found in stainless, are plow bolts, these too are typically square faces below the dome, not hex.

For sanitary service, NSF prefers flat head or pan head fasteners with cross-recessed drive details.

 

[jlnsol]

@prex: yes isn't it strange that nuts with spherical cap are good available but bolts not? Based on the DIN 917 for low dome nuts I designed attached bolt M4x10 mm. I remember these bolts from exhibitions and can hardly believe that machine builders let produce such bolts as customer specific parts. Cupped bolts I cannot use in food.

@screwman1: looks like this is our best option...but still hope there's a source with off the shelf

@btrueblood: metric and stainless are a must (europe and food) and to behonest I am surpised that NSF accepts pan head bolts with cross recessed internals. That is a good bacteria growth location!

.

 

[btrueblood]

The recess is technically cleanable because the sides of the recess are tapered. But, NSF doesn't allow any fastener in the food zone, due to the crevice beween fastener head and faying surface. Outside that zone, they may or may not require testing to certify the object is cleanable.
from NSF ANSI 2-2007:

5.5.2 Fasteners shall be easily cleanable. Fasteners meeting this requirement include, but are not limited
to, slot-head and Phillips-head screws, hex head fasteners, and flush-break pop rivets. Hex key
screws and non flush-break pop rivets may be used in a splash zone or a nonfood zone provided that the
heads are capped or filled.