When fragile items are shipped, special precautions must be taken to protect them. (Read Part I in our series on container mounts to understand what kinds of items need these precautions and what forces may be at work to damage the items). Container mounts can offer the required protection, but they must be carefully sized and selected—or even specially designed—to meet stringent engineering criteria.
Mounts must exhibit the proper stiffness, or flexibility, to absorb energy created by the shock and vibration being transmitted to a container’s payload. They act by storing or dissipating the forces imposed on the payload and releasing this stored energy in a controlled manner, so that the peak forces transmitted are below the critical level (or fragility) for the product being shipped. Key design considerations are the specific formulation of the elastomer used and the geometry of the mount.
The standard line of LORD Corporation’s shipping container mounts uses a specially compounded synthetic elastomer called SPE® I. This silicone-based material has high strength, medium damping and low temperature flexibility. For the geometry of the mount, energy dissipation is best achieved when mounts are positioned to resist shear forces; however, it is sometimes necessary to angle the mounts in a “focalized” formation to prevent rotation of a specific object. This angled formation aligns the elastic center of a mounting system more closely with the center-of-gravity of the mounted equipment. In some instances, optimal shock and vibration protection will require mounts to be placed on pivoting supports (gimballed) or may even require a special mount design conceived to provide low spring rates and high deflections in all directions. LORD can assist customers with mount selection as well as custom-engineer a mount system.
A thorough dynamic analysis is recommended any time that a mounted object is very fragile, predictable results are essential to protect your investment, or if the container system must pass rigid shock and/or vibration tests. LORD’s proprietary software will assess vibratory inputs, fragility and stability. The analysis will also consider a wide range of temperatures (-65 to +165F) under which the system must perform.
LORD offers a Shipping Container Suspension System Questionnaire that outlines the minimum data required for mount selection (payload weight, container size, input for shock, etc.). Customers can use this form to perform a self-analysis or transmit it to LORD for a detailed, formal system analysis. Our engineering assistance is available from initial design stages through post-transit customer service.
The rugged assembly of LORD’s container mounts offers controlled protection in all directions and a long service life, even under severe conditions. Furthermore, our bonded elastomeric mounts are simple, versatile, economical and easy to install.