Model MWF is a widely recognized general purpose low capacity weigh belt feeder designed to operate accurately and reliably in harsh industrial environments with minimal maintenance. It can be used with an open loop belt drive to gravimetrically measure the flow of material, or with closed loop control to operate as a feeder and regulate the flow to aconstant or dynamic set point.
The MWF-OS Sanitary Open Construction Weigh Belt Feeder provides Thayer Scale accuracy, ruggedness, and reliability. Self cleaning pulley eliminates material build-up and belt tracking problems. Unique flared skirt design prevents material spillage and assures proper feed control. Rigid scale support system provides
exceptional stability, assuring accuracy without frequent re-calibration.
Thayer Scale’s Model “MXL” is a widely recognized general purpose low capacity weigh belt designed to operate accurately and reliably in harsh industrial environments with minimal maintenance. It can be used with an open loop drive to gravimetrically measure the flow of material, or with closed loop control to operate as a feeder and regulate the flow to a constant or dynamic set point.
Designed exclusively for accurate and reliable feeding of materials with very low bulk densities such as wood flakes and fibers, snack foods, textiles and tobacco products. The MXL “Low Density” Weighbelt Feeder incorporates the following unique design features that result in high accuracy, reliable performance and stable calibration.
Simplified construction and calibration results from suspending a complete synchronous-speed conveyor from a Thayer Flexure Scale. The type”SB” unit adapts well to existing vibratory, screw or belt conveyor installations where it has been determined that weight measurement and/or flow control is desired. Also on new installations, the combination of a suitable pre-feeder and type SB unit often proves the best approach considering both cost and material han
Thayer Scale’s Weigh Belt Feeder Series “SI” Insertion Weigh Belt Module is a unique feeder that has been designed to easily fit into an existing belt or vibratory conveyor line. The “SI” comes in either scale over or scale under design. A short support framework and a V-Guided conveyor (12, 18 and 24 wide) makes this the only practical weighing module for insertion into a transition space between existing conveyors or equipment.
Slack Belt Design for more stable accuracy
Low belt tension means better more stable accuracy. The Thayer weigh belt is driven from the head pulley located at the outlet end of the feeder, rather than the tail pulley located at the inlet end, as in competing designs. This permits lower belt tension during operation for better sensitivity and more stable accuracy. The head pulley is crowned to prevent belt tracking problems and in sheathed in rubber lagging to prevent belt slippage.
Speed Sensor mounted at idling tail pulley
Measures the true speed of the belt via rotation of the idling pulley, not an inferred belt speed based on motor speed. Belt slippage or breakage is immediately detected because the idling pulley stops rotating.
Scale outside material handling area
An idler supporting the belt (the “weigh” idler) transmits the load to the scale, which is located outside the weigh belt enclosure. This design has several benefits. The scale is not prone to damage, is out of the way for cleaning, and is not subject to tare build-up since material cannot fall onto the scale.
High Accuracy, rugged measurement system
100% of the scale’s capacity is used to weigh material. Dead weight of the weigh idler and belt is mass-counterbalanced, thus providing excellent resolution and a high signal to noise ratio. Thayer Scale’s rugged load cell design assures reliable and accurate performance for the life of the weigh feeder.
Automatic Test Weight Calibration
Thayer Scale’s optional automatic test weight mechanism provides the means for applying a precision test weight to allow completely automatic calibration. The calibration sequence can be initiated via the weigh belt instrument keypad or via a contact closure. The need for test chains is eliminated.
Full length adjustable skirt boards
Tapered and flared from the inlet to the discharge to prevent pinching of material between the skirt and the belt. The skirt boards are located inside the belt flanges to provide two barriers to contain material and prevent spillage.
Inlet dimensions custom tailored and computer selected
Ensures uniform withdraw of material from storage. Very careful consideration is given to density, particle size and handling characteristics of your material.
Screw adjustable idler alignment
The idlers adjacent to the weigh idler are mounted on jacks for easy alignment in the field. All idlers are mounted on individual CEMA brackets, permitting removal to either side without major framework disassembly or belt removal.
The Thayer flexure suspension system (Patented) with its linear variable displacement transducer utilizes a series of high tensile strength steel flexures coupled to summing levers to accurately focus force to a tension type load sensor. Force measurement is decoupled from load position and mass counterbalance to accurately measure net material weight.
Design principle:
Load is opposed by tension forces in corner flexures (A). Tension forces in corner flexures produce moments about fulcrum flexures (B). Moment of left hand lever is transferred to right hand lever via equalizing flexure (C). Summed moment in right hand lever is therefore proportional to load irrespective of load position. Moment in right hand lever is opposed by tension in link flexure (D). Tension in link flexures (D) produces a moment in the final lever. Fulcrum flexure (E) transfers force to displacement transducer.
Features:
- Sustained sensitivity without maintenance.
- Cancels horizontal force vectors.
- Nulls out heavy tare loads.
- Immune to off center loading effects.
- 1000% over load capacity
A load sensor cannot distinguish between the “meaningful” force of material weight and other forces. THAYER Weighbelt Feeders are engineered to isolate the load sensor from these other forces, which affect repeatability for highly accurate weighing.
Dead weight is mass counterbalanced, so we can custom-size load sensor range to match application needs. To illustrate the benefit, imagine weighing a small package first on a truck scale and then on a postal scale. Although both are sensitive scales, only the postal scale range matches the application and therefore provides far more accurate results.
Excessive belt tension forces are eliminated by our head pulley drive and low deflection scale. Friction is defeated by using precision rollers instead of slider decks. Torsional forces, caused by off center loading and side forces, are decoupled from the true force transmission by our flexure-based lever system.
Force vector isolation is a Thayer Scale technological advantage. It is one of the best reasons to buy from the weigh feeder experts at Thayer.
