What should be paid attention to when the precision engraving machine is used for cutting die processing?

When the precision engraving machine is used to process the die, it is necessary to give consideration to the accuracy, efficiency, tool life and the service performance of the final die. The following items need to be paid attention to, covering the whole processing process and special requirements:

First, the adaptability of equipment and tools

The precision (usually ±0.01~0.05mm) and the quality of the cutting edge are extremely demanding in the machining of the tool die, so it is necessary to ensure that the equipment and the tool match the machining materials (such as steel, copper, wood, acrylic, etc.).

Equipment selection:

Spindle: Machining metal cutter dies (such as alloy steel and high-speed steel) requires a high-rigidity spindle (power above 5.5kW) with a rotating speed of 20,000 ~ 40,000 rpm; The medium and low power spindle (about 3.7kW) can be selected for processing wood/acrylic knife dies, and the rotating speed is 15,000 ~ 30,000 rpm.

Transmission system: ball screw+linear guide rail (rather than rack transmission) is preferred to ensure that the positioning accuracy of X/Y/Z axis is ≤0.005mm, and the repeated positioning accuracy is ≤0.003mm, so as to avoid blade deviation.

Additional shaft: If machining rotary die (such as rotary die), a four-axis linkage system is required to ensure the roundness (≤0.002mm) and coaxiality of the cylindrical cutting edge.

Tool selection:

Material: cemented carbide milling cutter (tungsten steel) or high-speed steel milling cutter (HSS) for metal processing, white steel cutter or single-edged milling cutter for wood/acrylic processing (to reduce chip sticking).

Blade type: the cutting edge of the knife die needs to be sharp, and the sharp-edged milling cutter is preferred (the blade angle is 30 ~ 60, which is adjusted according to the thickness of the cutting material: a small blade angle is used to cut thick materials to enhance strength); Root cleaning with ball end mill or flat-bottomed sharp knife, to avoid residue.

Second, the core preparation before processing

1. Drawings and process design

Cutting edge parameters: Make clear the height (usually 0.5~5mm, depending on the thickness of the material to be cut) and angle (for example, 45 for paper and 60 for leather) of the cutting edge, so as to avoid cracking during processing due to the thin cutting edge.

Tool withdrawal and clearance: design enough tool withdrawal groove (depth ≥0.3mm) to avoid scratching the machined surface when the tool returns; Complex tool dies (such as special-shaped holes) need to reserve a void-avoiding area to prevent tool interference.

2. Material fixation

Metal die (such as steel plate): fixed by bolt pressing plate (with a fulcrum every 50mm), or vacuum adsorption (the material needs to be flat, and the adsorption force is ≥0.08MPa), so as to prevent vibration during machining (vibration will cause ripples on the cutting edge).

Wood/acrylic knife die: fixed with double-sided tape and pressure plate to avoid displacement caused by insufficient vacuum adsorption.

Note: the material should be leveled in advance (flatness ≤0.02mm/m), otherwise the cutting edge height will be inconsistent after machining.

Third, the optimal setting of processing parameters

Parameters should match the requirements of materials, cutting tools and cutting edges. The core parameters are as follows:

Parameter metal die (alloy steel) wood die acrylic die

Spindle speed 15000 ~ 25000 rpm 20000 ~ 30000 rpm 18000 ~ 25000 rpm.

The feed speed is 500 ~ 1500mm/min, 2000 ~ 4000mm/min and 1500 ~ 3000mm/min.

Cutting depth 0.1 ~ 0.3 mm/layer (cemented carbide) 0.5 ~ 1 mm/layer (white steel knife) 0.3 ~ 0.8 mm/layer (single-edged knife)

Cutting mode Spiral cutting (radius ≤ 1/3 of tool diameter) Slant cutting (angle 30) Vertical cutting (low speed)

Key principles: the cutting depth should not exceed 1/3 of the tool diameter (to avoid breaking the tool); The feed speed shall be matched with the rotational speed (feed speed = rotational speed × feed per tooth × number of teeth) to prevent "gnawing" marks on the cutting edge.

Fourth, the real-time monitoring of the processing process

Abnormal monitoring:

Listen to the sound: normal cutting is a smooth "rustling sound". If there is an abnormal sound of "clicking", it may be that the tool is worn or the feed is too fast, so it is necessary to stop the machine immediately for inspection.

Look at the vibration: when the vibration amplitude of the spindle exceeds 0.01mm (which can be detected by a vibrometer), it is necessary to reduce the rotation speed or feed to avoid the precision of the cutting edge being out of tolerance.

Check the temperature: the temperature of the spindle shell is ≤60℃ during metal processing (exceeding the need to stop cooling) to prevent thermal deformation from affecting the accuracy.

Tool wear: check the cutting edge of the tool (with a magnifying glass) every 30~50 minutes. If there is edge collapse or edge curling, it needs to be replaced immediately (worn tools will cause serious burr on the cutting edge).

Cooling and chip removal:

Metal processing: cooling with emulsion (flow rate 5~10L/min) to avoid cutting edge annealing (hardness reduction) caused by cutting heat.

Dry processing (wood/acrylic): use high-pressure air gun to remove chips in real time to prevent debris accumulation from affecting the line of sight or scratching the surface.

Five, processing and testing after processing

Deburring and grinding: lightly grind the cutting edge with fine sandpaper (800#~1200#) to remove the burr left by machining (burr will wrinkle the edge of the cutting material), but keep the sharpness of the cutting edge (avoid dulling the cutting edge due to excessive grinding).

Precision detection:

Size: Check the distance between the cutting edges (such as the diameter of the inner hole of the die) with a two-dimensional projector, and the error shall be ≤ 0.02 mm..

Angle of cutting edge: measured by angle ruler or microscope, the deviation is ≤ 1 (inaccurate angle will lead to incomplete cutting or material adhesion).

Flatness: use marble platform+dial indicator to detect the bottom surface of the cutter die, and the flatness shall be ≤0.03mm (otherwise, the stress will be uneven during installation, which will affect the cutting effect).

Six, equipment maintenance and safety specification

Regular maintenance:

Guide rail: Add lubricating oil (such as No.32 guide rail oil) every day, and clean the guide rail sundries every week (to prevent scratches).

Spindle: Replace bearing grease every 500 hours to avoid heating and abnormal noise at high speed.

Screw: Check the pre-tightening force every month to prevent positioning error caused by excessive clearance.

Safe operation:

Wear goggles and non-slip gloves (to prevent tool debris from splashing).

Before machining, make sure that the emergency stop button is effective and the equipment is well grounded (grounding resistance ≤4Ω).

It is forbidden to place tools, water cups and other sundries in the processing area (to avoid interference).

summary

The core of die machining is "accuracy+edge quality", which requires the control of the whole process from equipment adaptation, parameter optimization, process monitoring to later detection, as well as equipment maintenance and safe operation, so as to ensure the cutting effect and service life of die.