Will my steel ejection mold bolts shear under sideways load?

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Discussion Overview

The discussion centers around the structural integrity of bolts used in a steel ejection mold, specifically addressing concerns about potential shear failure under sideways loads when the mold is lifted or flipped. The scope includes mechanical design considerations and safety implications related to the load distribution on the bolts.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • The mold weighs 5,900 lbs and utilizes four 5/8" diameter bolts with specific dimensions and thread engagement.
  • One participant raises a safety concern regarding the design, suggesting that the independent nature of the cylindrical steel pillars could significantly increase bolt tension during lifting.
  • A multiplication factor for bolt tension is proposed, calculated based on the length of the pillars and the difference between the pillar radius and the bolt hole radius.
  • A recommendation is made for a competent Mechanical Engineer to review the design and consider implementing additional structural support, such as diagonal braces or plates.

Areas of Agreement / Disagreement

Participants express concern about the safety of the current design, but there is no consensus on the best solution or design modifications needed to address the issue.

Contextual Notes

The discussion does not provide specific calculations or detailed design parameters for the proposed solutions, leaving some assumptions and dependencies on further engineering analysis unresolved.

jessemk
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hello.
I have a ejection mold (steel) which has a bridge like mount which locates the handling eye bolts outward around hydraulic cylinders. I need to make sure the bolts in the bridge will not shear due to the sideways load when the mold is lifted or flipped 90degrees. Here is the known information:
mold weight: 5,900 lbs
Bolt Dia: 5/8"
Bolt total length: 10.5"
Bolt thread engagement: 1.125"
Number of bolts in bridge 4

Color representation:
blue:Injection mold
orange: cylindrical steel pillars with a clearance hole through
purple: eye bolt mounting plate
Red:Bolt-socket head cap screw
upload_2015-9-18_12-20-18.png
 

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jessemk said:
hello.
I have a ejection mold (steel) which has a bridge like mount which locates the handling eye bolts outward around hydraulic cylinders. I need to make sure the bolts in the bridge will not shear due to the sideways load when the mold is lifted or flipped 90degrees. Here is the known information:
mold weight: 5,900 lbs
Bolt Dia: 5/8"
Bolt total length: 10.5"
Bolt thread engagement: 1.125"
Number of bolts in bridge 4

Color representation:
blue:Injection mold
orange: cylindrical steel pillars with a clearance hole through
purple: eye bolt mounting plate
Red:Bolt-socket head cap screw
View attachment 88827

Welcome to the PF.

What is your mechanical design background?
 
There is a very real safety issue with this design.
Because the cylindrical steel pillars are independent of each other they will greatly multiply the bolt tension at the start of the lift.
That multiplication factor will be something like their length divided by the difference between the pillar radius and the bolt hole radius. Factor = Lengthpillar * ( Rpillar - Rhole )

To eliminate the problem, a competent Mechanical Engineer, (with an insurance policy), would need to review the situation and possibly design something like a diagonal brace or a plate to unify the pillars.
 
Thank you, Baluncore.

And with that advice, this thread is closed.