Xin xiang custom ceramic mug factory, the production of ceramic coffee mugs in the selection of good raw materials, raw materials will be mixed and processed, after dewatering and practicing clay. Then came to the introduction of the “billet molding” link. At this time, the prototype of the ceramic mug was formed, but not perfect, how to make the mud blank more exquisite? Then, drying and trimming the two links, is the next important step. Ceramic mugs of the role of the drying process is: to reduce the moisture in the mud, in order to prevent the firing process in the ceramic mugs cracked; repair is to make the ceramic mug size, weight and other parameters in line with customer demand, and will be ceramic mugs imperfect place for “beautification”. Therefore, these two links are very important, then how to operate, and what are the precautions? Please listen to my slow talk:
1. Drying operation guide
Purpose: to remove moisture from the body of the blank, to prevent the kiln firing burst.
1.1. Preparation before drying
- Placement of the blanks:
- Place the wet blanks of ceramic mugs (moisture content of 18%-22%) on a hollowed-out plastic tray, with the mouth of the mug facing downwards, to avoid water accumulation inside the mug.
- The blanks should be spaced ≥ 5cm apart to ensure even air circulation.
- Environmental control:
- Natural shade drying: choose a ventilated workshop without direct sunlight, humidity 60%-70% (can be monitored by hanging hygrometer).
- Drying room: preheat to 30℃, humidity set at 50% (assisted by industrial dehumidifier).
1.2 Practical operation of drying process
a. Initial drying (0-12 hours):
- Focus on removing surface moisture and observe every hour whether the billet is deformed.
- Natural drying: Close some of the vents at night to prevent a sudden drop in temperature.
- Drying room: Increase the temperature by 2℃ every hour to 40℃ and keep it stable.
b. Intermediate drying (12-24 hours):
- Turning the blanks: Place the mugs on their sides to avoid one-sided shrinkage too fast resulting in crooked mugs.
- Check the seam line: if the joint between the handle and the mug is white (difference in moisture content), gently rub the transition area with a damp sponge.
c. Final drying (24-48 hours):
- Moisture content test:
- Feeling method: touch the bottom of the cup without wet and cold feeling, fingertip flick cup wall issued a crisp “ding” sound.
- Instrumentation: infrared moisture meter detection (sampling the center of the bottom of the mug, reading ≤ 2%).
- Correction of deformation: If the mouth of the mug is slightly elliptical, it can be adjusted with the palm of the hand while the blank is slightly wet (moisture content of 5%).
1.3. Precautions
- Anti-cracking:
- Avoid direct fan blowing on the blank, give priority to natural convection.
- Thick parts of the mug (such as the root of the handle) can be wrapped with a wet cloth to slow down the drying process.
Anti-pollution: drying room filter is cleaned weekly to prevent dust from adhering to the blank.
2. Operation Guidelines for Trimming
Purpose: trimming the shape of the blank, remove burrs and seam lines.
2.1. Tool Preparation
- Wet trimming tools:
- Stainless steel scraper (blade width 10mm, thickness 0.5mm) - to cut off the parting line.
- Natural sponge (aperture 1-2mm) - to wet the joints to prevent chipping.
- Dry repair tools:
- Carbon steel trimming knife (curved tip) - trimming the curvature of the mug.
- Sandpaper (120 mesh coarse grinding, 400 mesh fine grinding) - handle polishing.
- Vacuum cleaner - real-time dust cleanup.
2.2 Wet dressing procedure (moisture content 8-12%)
a. Remove the mold line:
- Left hand fixed mug, right hand holding scraper and the wall of the cup at an angle of 30 °, along the mold line lightly scraping, strength to “see the mud flying out, not hurt the blank” prevail.
- Key point: the scraping direction is the same as the opening and closing direction of the mold (usually vertical direction).
b. Handle joints:
- Wet the joints with a sponge dipped in water, and cut the excess clay with a spatula at an angle of 45°, so as to form a smooth transition (the difference in thickness is ≤0.3mm). c. Flattening the mouth of the cup.
c. Flatten the mouth of the mug:
- Invert the mouth of the mug on the rotating disk, scraper horizontal fit the edge of the mug, rotate at a constant speed to remove burrs.
2.3 Dry repair operation steps (moisture content ≤ 2%)
a. Finishing the mouth of the mug:
- Use 400 mesh sandpaper wrapped in wood, along the inner wall of the mug clockwise sanding, to eliminate the “knife cutting edges.
- Detection standard: finger scratching the mouth of the mug without scratching, no reflective burrs under the light.
b. Foot trimming:
- Cut the bottom of the mug vertically with a carving knife to a depth of 2-3mm, forming a 45° chamfer (to prevent sticking to the kiln plate after firing).
- Sandpaper the edges of the foot until rounded (roughness Ra ≤ 6.3μm).
c. Handle polishing:
- Use toothbrush dipped in water to remove dust from the grooves of the handles, and sandpaper with 120 grit sandpaper along the grain until there is no graininess.
2.4 Quality control and problem handling
- Repair common defects:
- Fine cracks: Fill with brush dipped in mud, and partially sand after drying.
- Uneven seams: fill with mud (mud:water=3:1), re-scrape flat.
- Full inspection standard:
- Dimensional tolerance: tolerance of mug diameter ≤±0.8mm (10% sampling with vernier calipers).
- Weight deviation: weight difference of the same batch of mugs ≤ 3% (weighed by electronic scale).
3. Cleaning and quality inspection
Purpose: to ensure that the blanks are dust-free and free of defects, in preparation for glazing.
3.1. Dust removal:
- Use compressed air to blow the surface floating dust, or use a soft brush to sweep lightly.
3.2. Water immersion test:
- Immerse the blank in water for 2-3 seconds and observe whether there are bubbles (if there are, there are dark cracks).
3.3. Full inspection standard:
- Appearance: no cracks, bubbles, deformation;
- Dimension: error of mug diameter and height ≤±1.5%;
- Strength: no collapse of the mug wall when pressed by fingers.
3.4. Points of Attention:
- Non-conforming products need to be crushed and returned to the clay system (add proportion ≤ 5%);
- After the quality control of the blanks need to be glazed within 24 hours to avoid moisture absorption.
The drying process of ceramic mugs is a key link that affects the yield. Some ceramic mugs will blow up when pouring hot coffee, besides the raw material problem, the biggest problem is the drying process. The manual trimming link tests the technician's responsibility and proficiency. China Ceramic Mug Factory has introduced electronic equipment, including electronically controlled drying room and automatic trimming assembly line (for details, please check the video released by our factory). The drying process is strictly controlled by electronic equipment and the efficiency and consistency of the trimming process has been improved. If you need custom ceramic mugs, then please find a more professional, attentive and advanced ceramic factory.
