Type #1…   The Slip-O-Matic Centrifugal Pump

            Since the early 1960’s, Lehman Manufacturing has made equipment that is designed specifically to transfer liquid clay. The first pump built went into a 1,000 gallon tank to feed overhead lines that ran throughout commercial pottery. That pump was to become known as our Slip-O-Matic, and it is still the best design in the industry today.

                The drive assembly of this pump is what we refer to as the bearing assembly and it has no bearings or moving seals exposed to the liquid. We use this unique assembly to drive several different types of pumping systems. The original unit was a centrifugal design with housing and impeller. A four-leg tower is used to suspend the housing, and the impeller is fastened to the shaft.

                Regardless of the shaft-size used, the hole in the top of the housing is slightly larger, and no bearing or seal is used at this point. As a result, the pump can be run either in or out of the liquid with no wear or damage to the system. While this pump is not cheap to build, there is nothing available that compares to its quality and durability. We back up this claim with a full two-year warranty.

                Also, since the pump is actually suspended in the slip, the rotating drive assembly creates mixing action in the tank. And by building different sizes of the same design, the pump can be made to meet the volume needs of various requirements and situations.

                This centrifugal Slip-O-Matic pump is used on many different models: T60, T100, BP24 as well as other commercial pumping systems. This same pump has been used in bulk delivery units that can use either electric, hydraulic or gas engine for power.

                When you want the best slip pump made, choose the Slip-O-Matic Centrifugal.

Type #2…   The Reversible Pump

            Shortly after we developed the original Slip-O-Matic Centrifugal pump, we modified it and introduced a unit that both fills and drains molds. The reversible Model “M” Slip-O-Matic became the most popular machine on the market back in the mid 1960’s. Today, we offer three models that utilize the same mechanical reverse action, and they are in daily use worldwide.

                These machines use the same bearing assembly, but it drives a positive displacement pump that consists of a rotor and a stator. When turning one direction, the slip is pumped through the hose and into the mold. When the motor is switched to drain, the assembly turns the other direction and pulls the slip from the mold back into the tank. An extension tube for the nozzle is provided to reach down inside to the bottom of the mold.

                Due to the fact that the rotor is turning directly inside the stator with slip running between them, there is an abrasive wear factor on these two parts. Over the past fifty years, we have improved the durability of the parts, but the average casting studio replaces them about once every 12 to 14 months. The rotor (part no. FS441) is the hardened stainless steel part and it usually has a slightly longer life than the stator (part no. FS442-1).

                Our Model RM30, RD30, and RD630 reversible machines are fantastic when used properly. They allow you to fill and drain large molds that would be nearly impossible to do by hand. If the drain feature is needed and going to be used, the maintenance expense is more than worth the benefit that is gained. If the machine is going to be used many hours a day in a commercial application and the reverse used only occasionally, then it may not be the model for you.

Type #3…   Outboard Bearings Pumps

          Our Studio Star (designed for the hobbyist) line of casting machines all use a centrifugal pump where the shaft is supported by a bearing at the point where it enters the housing. Some of these are externally mounted, and some of these pumps are suspended in the liquid. Regardless of the mounting style, a packing and seal system is needed to protect the bearings from the abrasive slip. The design is known as an “outboard bearing” design.    

                This type of pump is very economical to build, but unfortunately, the wear factor from the abrasive slip takes its toll on the packings. Eventually the slip will reach all the bearings, and major wear will occur. If this type of pump is used in a heavy or more commercial type operation, the maintenance problems can become a major factor to consider. Repair costs and down time must be taken into consideration, and it may be cheaper to use the Slip-O-Matic pump.

                In 1990, we completely redesigned our external version of this pump (the Studio Star EX4) to improve the mechanical design as much as possible. The outboard ball bearing is now held in place with a much better alignment bracket. The shaft bushing location was changed to provide better internal support, plus it can be replaced when it wears. The packings are more effective and are also easier to adjust and replace.

                Our Studio Star EX4 pump is the only real choice for economical external mounting applications. When used for hobby type workloads, it is a good value. It will simply not hold up under continual use when pumping abrasive slip.

                We also offer the outboard bearing type in a suspended style pump. This centrifugal pump looks similar to the Slip-O-Matic, but they do have the packings and seals exposed to the slip. Again, if they are used for hobby casting, they are a good value. They will require periodic maintenance and eventually the parts will have to be completely replaced because of abrasive wear from slip.

                Suspended versions (Model SP4) can be made to fit various depth tanks. They can also be modified to pump a few gallons less or a few gallons more than the standard model in our catalog.

 

Summary

Type #1 – Brand Name- Slip-O-Matic Centrifugal: This pump is the best. It has no bearings or seals exposed to the slip. Full two-year warranty. Used in our Model T60, T100, BP24, and several other commercial machines.

Type #2 – Brand Name- Slip-O-Matic Reversible: It pumps slip in the molds and also pumps it out of the molds. Eliminates heavy lifting. There is pump part wear because the rotor and stator are exposed to the slip. A great value for those that cannot lift heavy molds and need the reverse action.

Type #3 – Brand Name- Studio Star: With outboard bearings and seals there will be repair and maintenance required. A good value for small volume casting applications. Available in both internal and external mount designs. This pump is not recommended for heavy commercial use due to the abrasive wear factor. It is easy to repair or replace, and the cost is reasonable.