How to choose the webbing material for lifting slings?
The first step in choosing an appropriate web sling is to determine what material you need the sling to be made of. There are several different lifting slings to choose from including nylon slings,polyester slings,wire rope slings,and chain slings By looking at the properties of a lifting sling, it will help you determine what kind of sling to purchase. Nylon slings are strong and relatively inexpensive which makes them a very popular choice. Polyester slings don’t stretch as much when tension is applied and also have different tolerances to certain chemicals. They are also very flexible which prevents them from locking up on a load. Wire rope slings offer high strength and flexibility at a smaller diameter than polyester. Wire rope slings tend to be a little higher priced than nylon or polyester but are pivotal parts of the sling industry. Last but not least, chain slings are the heavy duty slings of the bunch. Chain slings are extremely flexible and offer superior strength for any situation. Chain slings can be more expensive than the other slings but their strength is second to none. If you are unsure about which sling you need, just call us or email our sales staff and they will gladly assist you.
Lifting Sling Use
Nylon – Nylon web slings are the most popular multi-purpose synthetic sling and are unaffected by oil and grease. Nylon lifting slings are very resilient to some chemicals such as aldehydes, ethers, and strong alkalies. However, they are not suitable for applications involving acids or bleaching agents. You will not want to use these webbing slings in temperatures in excess of 194°F (90° C). Nylon tends to stretch more than polyester and will stretch approximately 8-10% at rated capacity. Each category of nylon slings includes a nylon sling capacities chart with our nylon sling ratings.
Polyester - polyester round slings are used primarily where acidic conditions are present as polyester is not harmed by common acids and hot bleaching agents. However, these round slings are not suitable to use around concentrated sulfuric acids or alkaline. Polyester rope slings are not to be used in temperatures exceeding 194°F (90° C). While a nylon sling will stretch approximately 8-10%, a polyester round sling will only stretch approximately 3% at its rated capacity.
Wire Rope – wire rope slings are made of many different varieties of wire rope. Our wire rope is made from the 6×19 and 6×37 classes (depending on the wire rope diameter). The 6×19 class is the most widely used because of its good combination of flexibility and wear resistance. The 6×37 class is used primarily in our larger diameter wire rope and is characterized by the large number of wires that make each strand. The extra strands per wire make the 6×37 class more flexible but it also lessens it resistance to abrasion.
Chain – Our chain slings are made of Grade 80 lifting grade chain, although Grade 100 seems to be gaining popularity but is not an industry standard. Grade 100 is available upon request. Chain slings are often used in situations of high temperature or under adverse conditions that would normally destroy or wear on one of the other types of slings. Chain lifting slings are strong, durable, flexible and can be collapsed for easy storage. However, the price for chain slings can be substantially higher than the other types. Due to market instability, chain slings are generally quoted on an as needed basis as the pricing can fluctuate periodically. Chain slings generally do not stretch at rated capacity, or very minimal to say the least, but do have the capability to stretch 15-20% prior to failure. This is an excellent warning characteristic to inform the operator that the sling is ready for repair or replacement.
How to Choose the Correct Lifting Sling Type
There are many types of web slings ranging from eye & eye, triangle, triangle choker, endless, reverse eye, light duty cargo basket, all the way to heavy duty cargo basket slings. How do you know which sling you need? A lot of that will depend on the application you intend to use the sling for.
The eye & eye slings is the most popular of the nylon webbing slings. A great choice for multiple applications. It can be used in a choker hitch, vertical hitch or basket hitch. By using the twisted eye, you also gain additional wear surface by turning the eye inside out allowing you to use the other side of the eye. A straight eye will lay flat just like the body of the sling when it is laid down, whereas a twisted eye will lay at 90°, or perpendicular, to the sling body. If you are going to hook the sling to a rough hook, you may want to consider a triangle sling or triangle choker sling to help prevent the eye from abrasion from barbs on the hooks. A screw pin anchor shackle may also be an alternative. If you are looking for minimal stretch, a polyester eye&eye sling may be just the key for you.
The endless lifting sling is the most versatile sling of all the nylon and polyester lifting sling It can be used in a choker hitch, vertical hitch, and basket hitch also. And unlike the eye & eye sling, the spot where the object wears on the sling can be rotated to help prevent further wear, thus extending the life of the web sling. Just like the eye & eye sling, ployester endless sling offer an alternative with minimal stretch and added strength for those specialty jobs and added convenience.
Triangle slings are great for adding protection from wear on the eye of a lifting sling. By having steel triangles at the ends of a sling, this web sling provides optimum protection from barbs on rough hooks or other rough edges that may rub and wear on a nylon sling. These nylon slings are very versatile by working in vertical hitches and basket hitches. However, in order to use a choker hitch, you would need the triangle choker nylon lifting sling.
Triangle choker lifting slings also offer the same protection from wear as the triangle sling but it can be used in a choker hitch as well as the vertical hitch and basket hitch. The triangle choker nylon sling has a larger triangle on one end with a slot cut in it allowing for the maller triangle on the other end to pass through for the choker hitch. Great for versatility, protection, and the pricing is great.
Reverse eye lifting slings are tough double-duty that have
Cordura sewn into the eyes and body for added resistance from abrasion. Cordora is a fabric that does not add to the strength of the lifting sling but does provide a tougher wear surface to help prevent damage from cutting and abrasion. The eyes of the reverse eye lifting sling stand open at 90° to the sling body to allow for easier choker and basket hitches.
Continuous eye wide body lifting slings or cargo slings, are used for basket hitches only. A wide body heavy duty basket nylon sling’s primary function is for applications that require a wide body for load stability or proper handling of fragile or finished surfaces. This heavy duty web sling is not the most versatile of the nylon lifting slings being it is a basket hitch application only. But this lifting sling can be essential when handling delicate cargo.
Attached eye wide slings also called light duty cargo basket lifting slings, are very similar to the continuous eye wide body slings, but are meant for light duty applications. These cargo slings also are great for precious cargo but have lower weight rating capacities than the type 8. The eyes are not a continuous part of the body but are sewn on with smaller webbing to help accomodate small hoist hooks.
How to Calculate the Load Factor for Lifting Slings in Basket Hitches
Now, you should have a good idea of the fabric you want for your lifting sling and the type, or style, of lifting sling you want to use. The next step is to make sure you get a lifting sling with a weight rating capacity strong enough to do the job you need it to do. This will be a very basic overview of how to determine the weight rating but we strongly suggest that if you are uncertain in any way, please don’t hesitate to contact our sales and they will be glad to help make sure you get the product you need.
This calculation process is meant primarily for basket hitch applications as the angles of the legs will not be a factor in a vertical or choker hitch. We will use the picture at left (Diagram A) to help us demonstrate how to calculate the load factor and weight rating of the sling needed.
Step 1: Figure the weight of the item you are lifting. In this example, let’s say the load weighs 1000 lbs.
Step 2: Next, you will need to know the angle of the sling legs to the object (noted in Diagram A as 60°).
Step 3: Look at the Load Factor Chart to the right and find the multiplier for 60° (in this case it is 1.154).
Step 4: Then, take your weight and multiply it by the load factor (1000 x 1.154 = 1,154 lbs.)
In this example, the lifting sling weight rating you would need would be 1,154 lbs. in a basket hitch rating. So whether you chose a nylon lifting sling or a polyester round sling, you will need to look in the Basket Hitch column to make sure the rating is 1,154 lbs. or more. Of course this is a very basic lift example and some more complicated loads, such as one that requires multiple lifting slings for one item, should be left up to a professional for more precise information. Again, we would strongly suggest contacting our customer service sales team to help you with any questions.