Rotary tablet presses are core equipment for tablet compression in the pharmaceutical, food, and other industries. Improper operation can not only affect tablet quality (such as cracking, loosening, and significant weight variations) but also lead to equipment malfunctions and even safety accidents. The following are critical operational errors that must be avoided, explained one by one in conjunction with actual production scenarios:
I. Errors Before Starting the Machine (Root Cause Risks)
- Skipping equipment inspection and starting the machine directly: This involves not checking whether the molds (punches and dies) are intact and clean, not confirming whether there are foreign objects in the hopper, and not verifying that the pressure and speed parameters match the current tablet specifications before starting the equipment. Hazards: Damaged molds can lead to jamming and tablet cracking; foreign objects can contaminate the material; incorrect parameters will result in substandard tablets (e.g., insufficient pressure leading to loose tablets, excessive speed leading to cracked tablets). Correct practice: Before starting, the integrity of the molds and the cleanliness of the materials must be checked, and core parameters such as pressure, speed, and filling volume must be calibrated. A trial run of 1-2 minutes without material should be performed before adding material.
- Replacing materials without cleaning residual material: When changing to different types or colors of materials, failing to clean residual material from the hopper, material bin, and turntable before adding new material. Hazards: Cross-contamination of materials, leading to impure tablet components (violating GMP regulations in the pharmaceutical industry), and potentially causing poor material flow due to residual material clumping. Correct practice: Before changing materials, disassemble the washable parts (hopper, scraper), clean them with a special cleaning agent, dry them, and ensure there is no residue before adding new material.
II. Errors During Operation (High-Risk Behaviors)
- Operating with the safety guard open: During equipment operation, opening the safety guard to clear blockages at the discharge port or adjust tablet weight, and inserting hands or tools into the turntable area. Hazards: The rotating turntable and punches have high-speed shearing force, which can easily lead to hands being caught or tools being struck and thrown out, causing serious injuries (this is the most fatal operational error of a rotary tablet press). Correct practice: Under any circumstances, the machine must be stopped and the power cut off. Only after the turntable has stopped should the safety guard be opened for cleaning or adjustment. Overloading/Forced Feeding Errors: Manifestations include excessive material in the hopper leading to blockage of the discharge port, or forcibly clearing the discharge port with hard objects such as iron rods or screwdrivers when the material has poor flowability; or feeding an amount of material far exceeding the equipment's processing capacity at once. Hazards: Hard objects may damage the inner wall of the hopper, scratch the die, or even cause the punch to break; overloading can cause the motor to overload and burn out, or the turntable to jam and stop. Correct practice: Stop the machine and clean it when the discharge port is blocked; for materials with poor flowability, pre-crush and sieve them, or add an appropriate amount of flow agent; feed materials in batches according to the equipment's rated capacity.
- Unauthorized Adjustment of Core Parameters During Operation Errors: Manifestations include arbitrarily adjusting the pressure knob, speed switch, or filling amount adjustment device while the equipment is running, attempting to "optimize" tablet quality while operating. Hazards: Sudden parameter changes can cause instantaneous fluctuations in tablet weight and hardness, resulting in a large number of defective products; a sudden increase in pressure may damage the die or spindle, and sudden changes in speed can cause equipment vibration and increased noise. Correct practice: The machine must be stopped before adjusting parameters, and only one parameter should be adjusted at a time (e.g., adjust the filling amount first, then the pressure). After adjustment, test the machine without material to ensure there are no abnormalities before resuming production.
- Ignoring Abnormal Signals and Continuing Operation Errors: Manifestations include continuing production without timely stopping and troubleshooting when the equipment makes abnormal noises (such as metal friction sounds, jamming sounds), tablets show continuous cracking/loosening, or the motor temperature rises abnormally. Hazards: Small malfunctions escalate into major malfunctions (such as punch breakage, spindle bending), increasing maintenance costs; abnormal tablets flow into the next process, leading to batch quality accidents. Correct practice: Stop the machine immediately upon discovering any abnormality, troubleshoot the cause of the malfunction (such as mold wear, excessive material moisture content, insufficient pressure), and restart after resolving the problem.
III. Incorrect Operations After Shutdown (Easily Overlooked Hazards)
- Storing the Equipment Without Cleaning Errors: After production, only the surface of the equipment is simply wiped, and material residue in the turntable gaps and die holes is not cleaned before the equipment is shut down and stored. Hazards: Residual materials absorb moisture and clump together, blocking the mold during the next startup; long-term residue can breed microorganisms (in the pharmaceutical/food industry) or corrode metal parts of the equipment. Correct practice: After shutdown, disassemble the punch and die, hopper, and other components, clean residual materials from crevices with a brush and compressed air, and if necessary, clean with a compliant solvent. After drying, apply rust-proof oil (for long-term storage).
- Incorrect handling of molds/improper storage: After shutdown, punches and dies are randomly piled on the workbench, without proper classification or cleaning and rust prevention. Hazards: Molds are prone to collision, deformation, and rusting, resulting in the production of substandard tablets during subsequent use, or even damaging the equipment. Correct practice: After disassembly, clean and dry the molds, store them in dedicated mold boxes, classify them by specifications and models, and regularly check for rust.
IV. Basic Operator Errors (All personnel must avoid these)
- Unauthorized personnel operating independently: Personnel who have not received professional training and lack operating qualifications operate the rotary tablet press independently. Hazards: Unfamiliarity with equipment principles and safety regulations can easily lead to operational errors and safety accidents. Correct practice: Before operation, personnel must undergo pre-job training and pass the assessment to obtain a certificate before working. New employees must operate under the supervision of an experienced operator.
- Leaving the workstation during operation/multiple people operating simultaneously: The operator leaves the workstation to handle other tasks while the equipment is running, or multiple people operate the same equipment simultaneously (e.g., one person adjusts parameters, another feeds materials), leading to confused instructions. Hazards: Unattended operation prevents timely handling of abnormal situations; multiple operators can easily cause misoperation (e.g., one person doesn't stop the machine while another reaches in to clean). Correct practice: The operator must be present throughout the operation. When multiple people are working together, a main operator must be designated, and non-main operators are not allowed to touch the equipment buttons or adjustment devices.
Core Summary
Most errors in operating rotary tablet presses stem from "taking shortcuts" and " a mentality of taking chances". The key to avoiding these errors is: strictly following SOPs (Standard Operating Procedures), conducting a comprehensive check before starting, monitoring throughout the operation, immediately stopping the machine in case of abnormalities, and cleaning after shutdown. This ensures stable tablet quality and prevents equipment damage and safety accidents.