Products That Aren't Round, Are Lopsided, or Have Tails

Customers decide whether a product looks good at first glance. A lopsided bun, a tangyuan that isn't round, or a mooncake with a tail on the bottom may taste the same, but it's a step behind on the store shelf. The causes of shape problems fall roughly into three areas: ingredients, settings, and the machine.

Why Products Come Out Not Round

• Wrapper too soft: After forming, it can't support its own weight and slumps, flattening the bottom and making the whole piece oval.
• Wrapper too elastic: The gluten shrinks back, slowly pulling the product out of shape after forming. See Flour Types and Machine Forming.
• Off-center filling: If the filling isn't centered, the wrapper is thick on one side and thin on the other; the thin side sags and the thick side bulges, so the piece leans.
• Filling too soft or too hard: Too soft and it can't hold a shape; too hard and the wrapper won't conform around it.
• Rough drop and pickup: When the product falls from the outlet onto the conveyor, if the conveyor speed doesn't match the discharge rhythm, the product gets dragged or pushed out of shape.

Tails at the Seal

A tail forms when the wrapper isn't cut cleanly during cutting and closing and a strand gets pulled out. Common causes:

• Wrapper too sticky: Glutinous rice wrappers and dough with too much water are especially prone to stringing. See Characteristics of Glutinous Rice Wrappers on Machines.
• Residue at the cutting point: Residue keeps the cutting action from closing completely.
• Cutting speed and timing don't match: RHEON patent US8359973B2 describes a mechanism that uses a cutting assembly below a co-extrusion nozzle to cut and shape a filled rope; another patent, US6709256B2, notes that the closing speed and timing of the cutting pieces need to be adjusted with production speed, and that large speed changes make a clean cut difficult. So if tails appear after you speed up or slow down output, suspect the speed setting first.
• Wrapper too dry: A wrapper with a dry surface won't stick together at the seal, leaving a small pointed tip.

How to Adjust

Ingredients

1. Adjust water content and dough temperature so the wrapper is moderately firm. See Wrapper Moisture Content.
2. Rest the dough sufficiently to reduce spring-back.
3. Cover the dough to prevent surface drying.
4. Keep filling consistency uniform. See Filling Viscosity, Particle Size, and Moisture.

Settings

1. Return output to the speed at which the shape was previously stable and see if it improves.
2. Following the operating manual, adjust the settings related to forming, closing, and conveying, one at a time, and observe a few dozen pieces.
3. If the filling is off-center, first check whether wrapper and filling are being fed steadily. See Wrappers Too Thick, Too Thin, or Uneven.

Machine (after stopping)

Before checking anything by hand, press stop, turn off the power, and unplug the machine or cut the main switch, and make sure the machine has come to a complete stop. In factories with multiple workers, lock the switch and hang a "Under maintenance, do not energize" tag. Article 57 of Taiwan's Occupational Safety and Health Facilities Rules (職業安全衛生設施規則) requires that when machinery is being cleaned, oiled, inspected, repaired, or adjusted, operation and feeding must be stopped, and measures such as locking out and posting signs must be taken to prevent accidental start-up.

Once the power is confirmed off, clean residue from the outlet and cutting point according to the operating manual, and make sure the detachable parts are reinstalled in their original positions and not loose. Visually check whether the conveyor belt is tracking off-center and whether its surface is flat.

When to Call for Service

If after cleaning and adjusting speed and ingredients the shape still leans consistently in the same direction, or tails remain obvious with normal ingredients, the cutting or conveying mechanisms may need calibration. These adjustments involve the relative positions and timing of the mechanisms, so please don't disassemble them yourself.

FAQ

Q: Why aren't my buns coming out round?
A: Commonly the wrapper is too soft to hold its shape, the gluten is too strong and shrinks back, the filling is off-center, or the discharge and conveyor speeds don't match.

Q: What causes a tail at the seal?
A: A wrapper that is too sticky or too dry, residue at the cutting point, or cutting speed and timing that don't match the output.

Q: What if the shape gets worse after I increase output?
A: First return to the speed that was previously stable; when you need more output, adjust gradually according to the operating manual and observe.

Q: What if it leans to one side no matter what I adjust?
A: Stop the machine and cut the power, don't disassemble the mechanisms, note the machine model, the product, and the symptoms, and contact the manufacturer or a service provider. Dong-Yih Machinery: 06-257-4644.