What matters should be paid attention to when processing and cutting non-metallic engraving machine with plastic suction knife die?

Key points for attention in processing rubber materials by nonmetallic engraving machine with plastic suction knife die.

When processing rubber (rubber pad/rubber strip matched with the die) by nonmetallic engraving machine of plastic suction die, the core should be to avoid the problems of rubber sticking, cut burr, hot melt deformation and size deviation, and take into account the precision of engraving and cutting (matching the assembly gap of plastic suction die) and the elastic integrity of rubber finished products. It is necessary to control and control the rubber parts of plastic suction die from five dimensions: preparation before processing, debugging of cutter and parameters, control of cutting process, equipment operation and finished product treatment.

1. Preparation before processing: substrate fixing and equipment foundation inspection.

Accurate fixation of rubber substrate

Rubber is an elastic soft material, which is easy to move due to cutting vibration. It needs to be fixed by vacuum adsorption platform and thin double-sided adhesive (vacuum adsorption is the main method, and double-sided adhesive helps to prevent warping). Before fixing, the surface of rubber plate should be wiped clean, free of oil and dust, so as to ensure that the base material is flat and wrinkle-free, and the edge is aligned with the positioning line of the platform. It is forbidden to press only with heavy objects, which may easily lead to local looseness and deviation. Before batch processing, the adsorption force of the platform should be calibrated, and thick rubber sheets (> 5 mm) can be attached with anti-slip felt at the bottom to enhance the fit.

Note: If small materials are processed in rubber strip, it is necessary to use fixture to prevent small parts from being picked up by tools.

Calibration of equipment and drawings

Check the accuracy of the three-axis operation of the engraving machine, the zero return error is ≤0.01mm, and the guide rail is free of jamming and clearance; Import the CAD drawings of rubber parts of plastic suction die into the control system, calibrate the actual cutting origin and the drawing origin, and use light touch tool alignment (the tool moves down slowly to contact the surface of the substrate to avoid rubber depression caused by heavy pressure). Before batch processing, try to cut one piece, and check the size and the assembly gap of the die (the size of rubber parts should be 0.05~0.1mm smaller than the die slot, so as to adapt to elastic assembly).

Working environment control

The processing area should be kept dry, and the ambient temperature should be controlled at 20~28℃ to avoid rubber cutting due to high temperature softening and low temperature hardening; At the same time, ensure that there is no dust accumulation in the workshop, and prevent dust from entering the equipment guide rail and spindle, which will affect the running accuracy.

Second, tool selection and installation: adapt to the soft characteristics of rubber.

The core of rubber cutting is smooth chip removal, non-stick cutter and low heat melting. The cutter selection directly determines the quality of the cut. It is forbidden to use metal-working cemented carbide milling cutters (easy to stick chips and hot melt rubber). Specific selection and installation requirements are as follows:

Optimum selection of special tools

Thin rubber (≤3mm): Single-edge spiral milling cutter (diameter 1.0~2.0mm) is used, and the single-edge design can remove chips quickly, so as to avoid rubber chips from winding the cutter and reduce hot melt adhesion;

Thick rubber (3~10mm): Double-edge straight groove rubber milling cutter (2.0~4.0mm in diameter) is used. The straight groove structure reduces the friction area between the cutter and rubber, reduces heat generation and ensures cutting strength;

Special-shaped contour/narrow groove cutting: use a micro-diameter single-edged carving knife (0.8~1.2mm in diameter) to adapt to the fine structure to avoid the rubber edge cracking caused by too thick cutter.

Specification for tool installation

When the tool is clamped, ensure that the coaxiality deviation is less than or equal to ≤0.02mm, and the protruding length is as short as possible (only 2~3mm beyond the rubber thickness), so as to reduce the shaking of the tool and prevent the deviation and burr of the incision; After clamping, manually rotate the tool without jamming and swinging, and then carry out the idle feed test to confirm that the tool running track is consistent with the drawing.

Third, core parameters debugging: low speed, slow feed and large feed.

Rubber is a heat-sensitive soft material. The parameters of the engraving machine should follow the principles of low rotation speed, slow feed, large cutting depth and air cooling, and abandon the high parameters of non-metallic hard materials (such as acrylic and density board) to reduce the friction heat between the cutter and rubber, and avoid hot-melt sticking of the cutter and carbonization of the incision. The reference parameters of rubber with different thicknesses (can be fine-tuned according to the actual cutter diameter):

form

Rubber thickness (mm) Spindle speed (r/min) Feed speed (mm/min) Single cutting depth (mm) Feed mode

≤ 38,000 ~ 12,000, 500 ~ 1,000, full-range cutting and continuous feed.

3 ~ 6 6000 ~ 10000 400 ~ 800 2 ~ 3 layered feed

6 ~ 10 5000 ~ 8000 300 ~ 600 1 ~ 2 layered feed

Key debugging points:

Spindle speed should not be too high (> 15,000 r/min is easy to generate heat due to intense friction, resulting in hot melting of rubber incision and sticking of the knife), and the feed speed should be matched with the rotation speed to avoid rubber edge collapse caused by "biting" of the knife;

When slicing, the cutting paths of two adjacent layers are staggered by 0.1~0.2mm to avoid repeated cutting and heat generation at the same position;

Turn on the spindle air cooling (cold air gun), adjust the air volume to the middle and low level, aim at the cutting place of the tool, blow away the debris in time, reduce the temperature, and it is forbidden to use water cooling (rubber is easy to deform and lose elasticity when it meets water).

Fourth, cutting process control: avoid the common problems of elastic material processing.

Combining the elastic and viscous characteristics of rubber, the cutting path and cutting mode are optimized to reduce the size deviation, burrs and hot melt problems from the process. The key points are as follows:

Tool path planning

Follow the principle of * * "from inside to outside, from fine to coarse, from small hole to outer contour" * *, first cut the fine structure of rubber parts, such as slots and special-shaped holes, and then cut the outer contour, so as to prevent the substrate from loosening after cutting the outer contour first, resulting in the deviation of the internal fine structure; When cutting the closed contour, reserve a 0.3~0.5mm cutter position to prevent the rubber parts from being picked up by the cutter or deformed due to elastic rebound after cutting, and then the rubber parts can be disconnected by manual light snapping without burr.

Corner and sharp corner treatment

Rubber is prone to edge collapse and rebound due to stress concentration at sharp corners/corners, so it is necessary to change the sharp corners in the drawings to small rounded corners of R0.2~R0.5mm (which will not affect the assembly of plastic suction die), turn on the speed reduction function of the engraving machine when cutting corners (the corner speed is reduced to 50%~70% of the normal feed), and feed slowly to avoid the rubber edge tearing caused by tool inertia.

Avoid repeated cutting

Rubber is elastic, and repeated cutting at the same position will lead to enlarged incision and increased burrs. It is necessary to cut through (thin material) or cut accurately in layers (thick material) at one time, and the cutting depth parameters are adjusted in place. It is strictly forbidden to make up the cutting many times; If the slight cutting is not complete, you can make up the cutting once after fine-tuning the depth, instead of repeatedly cutting.

V. Equipment Operation and Maintenance: Ensure the processing stability.

Real-time monitoring of machining process

When the equipment is running, observe the cutting state of the cutter in real time. If there is debris winding the cutter, sticking the cutter at the incision or local melting of rubber, stop the machine immediately, clean the rubber debris on the cutter (wipe it with alcohol to avoid residual adhesive), check whether the air cooling is normal, and reduce the rotation speed/feed speed if necessary; If the base material is found to be loose, stop the machine and re-fix it, so as to avoid the size scrap caused by continuous processing.

Tool cleaning and replacement in time.

Every 10~20 pieces of rubber parts are processed, the residual debris on the cutter is blown off with a high-pressure air gun (low-pressure mode), and the cutter surface is wiped with alcohol; If the cutting tool is worn and the cutting edge is passivated (manifested by serious burrs on the incision and frequent sticking of the cutting tool), replace the cutting tool immediately, and it is forbidden to continue processing with the passivated cutting tool, otherwise it will aggravate the rubber melting and deformation.

Daily maintenance of equipment

After the processing is completed, clean the rubber crumbs of the vacuum adsorption platform and check whether the platform gasket is intact (to prevent the adsorption force from decreasing); Regularly lubricate the guide rail and screw rod of the engraving machine, clean up the impurities in the spindle chuck, and ensure the smooth operation of the three shafts; Check the air outlet of air cooling system, no blockage and normal air outlet.

6. Post-treatment of finished products: ensure the adaptability and integrity of rubber parts.

Instant cleaning and glue removal

After cutting, use a high-pressure air gun to blow off the crumbs on the surface of rubber parts and the cut. If there is a slight adhesive/hot melt layer on the cut, lightly grind it with 400~600 mesh fine sandpaper (along the cut direction to avoid scratching the rubber surface), or wipe the adhesive with alcohol. It is forbidden to scrape it with a sharp knife to prevent damage to rubber elasticity or dimensional deviation.

Finished product detection and screening

Check the dimensional accuracy (tolerance ≤±0.05mm) of rubber parts, the smoothness of the incision, no burr, edge collapse and hot melt carbonization, no prick when touching the edge of the incision by hand, and no damage to elasticity; Check the assembly fit with the plastic suction knife die, and eliminate the unqualified products in time to avoid flowing into the subsequent assembly process.

Standardized storage

The finished rubber parts shall be stored in categories according to specifications, stacked with flat pallets (stacking height ≤50cm to avoid heavy deformation), and the storage environment shall be kept at normal temperature and dry (humidity ≤60%), away from oil, high temperature and sharp objects to prevent rubber from aging, sticking and damage; Avoid mixing rubber parts with other hard materials to prevent surface scratches.

VII. General requirements for safe operation

Wear goggles and non-slip gloves when operating the engraving machine to prevent rubber chips from splashing into eyes or cutting hands with knives;

When the equipment is running, it is forbidden to touch the cutting area by hand and adjust the substrate or cutter. If you need to deal with the fault, you must stop the machine and cut off the power first.

When the spindle is not completely stopped, it is forbidden to get close to the cutter to prevent the inertia of the cutter from hurting people;

Do a good job in grounding protection of equipment in the workshop to avoid electrostatic adsorption of dust, which will affect the machining accuracy or cause potential safety hazards.