Weight Control: How Does an Encrusting Machine Keep Every Piece the Same Weight?

Why Weight Matters

A 2 g difference in one bun may not look like much, but at 10,000 buns a day it adds up to 20 kg of ingredients. For factories selling through retail channels, the labeled weight cannot come up short; for costs, every extra gram is money. That is why the question customers ask most often when buying an encrusting or dividing machine is: "How accurate is each piece?"

How Accurate Can Per-Piece Weight Be?

There is no universal answer. Accuracy depends on the machine, the ingredients, and the operation all at once, and most manufacturers do not give just one figure. RHEON says of its new CN700 that after switching to cycloid feeding, the flow is more stable and "weight accuracy is greatly improved," and it has added a weight correction function. Its VM system for bread lines uses a "weigh while dividing" approach (the gravimetric method), cutting to a set weight.

When choosing a machine, the more practical approach is to do a test run with your own ingredients, weigh 50–100 consecutive pieces, and look at the average and the gap between the heaviest and lightest.

How Machines Control Weight

Encrusting and dividing machines control weight in roughly two ways:

Volumetric method: deliver the same volume every time. A screw pushes material into a vane pump, each chamber of the pump delivers a fixed volume, and the shutter cuts at fixed intervals. As long as the material's density stays constant and every chamber is filled, the weight stays consistent. Most encrusting machines and dividing machines work on this principle; see Feeding Mechanisms.

Gravimetric method: weigh directly, then cut. This is common on bread lines. For example, RHEON's EZ divider has a "weighing cut mode" that divides at a set weight within a range of 20–350 g, as well as a "fixed interval mode" that cuts by length.

Correction: Newer machines add "weight correction" on top of the volumetric method. After sample pieces are weighed, the system adjusts the feed volume so the actual weight returns to the set value.

Common Causes of Inaccurate Weight

When weight swings up and down on the production floor, the cause is usually one of these:

• Hopper nearly empty or overfilled: Changes in the material level affect how well the screw grips the material, and if the vane pump chambers do not fill, pieces come out light. RHEON's patent US6408899B2 points out that conventional small machines often have the problem of vane chambers not filling completely, resulting in uneven feeding.
• Non-uniform ingredients: Insufficient mixing, lumps, air bubbles, or a batch whose first and last portions differ in firmness.
• Temperature changes: As dough ferments or filling warms up, both density and flowability change; see Rheology and Encrusting.
• Ingredients with particles: When beans or diced meat are unevenly distributed, piece weights naturally vary.
• Worn parts: After the vanes, pump body, or shutter wear, gaps widen and the feed volume drifts.
• Dusting flour: Uneven dusting flour can also make finished weights look inconsistent.

Recommended troubleshooting order: check the ingredients first, then the material level, and only then suspect the machine.

Microcomputer Control vs. Mechanical Control

Mechanical: Speed is adjusted by gear ratios, continuously variable transmissions, or knobs, and shutter timing is set by cams. The advantages are an intuitive structure and durability; the drawback is that every product change relies on an experienced operator's feel to readjust, making it hard to reproduce exactly the same conditions.

Microcomputer control: The feeding, shutter, and conveyor are each driven by their own motors, with speeds and timing written as numerical values. In US6709256B2, RHEON notes that with older designs, changing output required complicated adjustments to motor direction, angle, and start/stop timing; only after switching to servo motors with operating patterns stored in memory could the shutter closing speed be adjusted on its own without changing the cycle.

Practical benefits of microcomputer control:

• Conditions are expressed as numbers that can be recorded and saved as recipes, then recalled with one touch next time.
• Functions such as weight correction and counting can be added.

One of Dong-Yih Machinery's lines of business is microcomputer-controlled fully automatic dividing machines, such as the DY-528MS Sweet Potato Ball and Taro Ball Dividing Machine, which produces 3,000–12,000 pieces per hour at 10 g–30 g per piece or heavier. Dong-Yih does not publish weight tolerance specifications for its models on its website; please call 06-257-4644 and bring your ingredients for a test run.

FAQ

Q: How accurate is the weight of each piece from an encrusting machine?
A: It depends on the model, ingredients, and operation, and most manufacturers do not give a single figure. The most reliable method is to do a test run with your own ingredients and weigh 50–100 consecutive pieces to see the spread.

Q: Why do pieces in the same batch get lighter and lighter?
A: Common causes are a falling material level in the hopper, vane pump chambers not filling, or ingredients warming up and softening, which changes their density. Top up the material and check its temperature first, then see whether correction is needed.

Q: Is microcomputer control always more accurate?
A: Not necessarily more accurate, but conditions can be expressed as numbers and stored, so it is easy to return to the same settings after a product change, giving better reproducibility.

Q: Do fillings with particles affect weight?
A: Yes. If particles are unevenly distributed, piece weights will vary. Thorough mixing and choosing a feeding method suited to particles can help.