1. The workpiece is overcut

 

the reason:

Flick knife, the tool strength is not too long or too small, causing the tool to flick.

Operator improper operation.

Uneven cutting allowance. (For example: leave 0.5 on the side of the curved surface and 0.15 on the bottom)

Improper cutting parameters. (For example: the tolerance is too large, the SF setting is too fast, etc.)

 

improve:

The principle of knife use: can be big or small, can be short but not long.

Add the corner cleaning program, and keep the margin as even as possible. (Leave the same margin on the side and bottom)

Adjust cutting parameters reasonably, and round corners with large margins.

Using the SF function of the machine tool, the operator fine-tunes the speed to achieve the best cutting effect.

 

Second, the problem of dividing the middle

 

the reason:

Inaccurate during manual operation by the operator.

There are burrs around the mold.

The center rod is magnetic.

The four sides of the mold are not vertical.

 

improve:

Manual operation should be carefully checked repeatedly, and the points should be at the same height as possible.

Deburr the periphery of the mold with oilstone or a file, wipe it clean with a rag, and finally confirm it by hand.

Demagnetize the centering rod before centering the mold. (Ceramic centring rod or others can be used)

Calibrate to check whether the four sides of the mold are vertical. (Large verticality error needs to review the plan with the fitter)

 

Three, the problem of knife setting

 

the reason:

Inaccurate during manual operation by the operator.

The tool is incorrectly clamped.

The blade on the throwing knife is wrong. (The flying knife itself has a certain error)

There is an error between R knife and flat-bottom knife and flying knife.

improve:

Manual operation should be carefully checked repeatedly, and the knife should be at the same point as much as possible.

When the knives are clamped, use an air gun or wipe them with a rag.

One blade can be used when the upper blade of the flying knife needs to measure the tool shaft and the smooth bottom surface.

A separate tool setting program can avoid the error between R knife, flat knife and flying knife.

 

Four, collision-programming

 

the reason:

The safety height is insufficient or not set. (The tool or the chuck hits the workpiece at rapid traverse G00)

The tool on the program sheet and the actual program tool are written incorrectly.

The tool length (blade length) and the actual machining depth on the program sheet are wrong.

The depth Z-axis access and actual Z-axis access on the program sheet are incorrectly written.

The coordinates are set incorrectly during programming.

improve:

Accurate measurement of the height of the workpiece also ensures that the safety height is above the workpiece.

The tool on the program sheet must be consistent with the actual program tool. (Try to use automatic program list or use pictures to output program list)

Measure the actual machining depth on the workpiece, add WeChat: Yuki7557 to send a copy of the macro program tutorial, write clearly the length of the tool and the blade length on the program sheet. (Generally, the length of the tool holder is 2-3MM higher than the workpiece, and the length of the blade is 0.5-1.0MM)

Take the actual number of Z axis on the workpiece and write it clearly on the program sheet. (This operation is generally written manually and needs to be checked repeatedly)

 

Five, collision-operator

 

the reason:

Depth Z axis tool setting error.

The number of hits and operations are wrong. (Such as: unilateral fetching without cutting radius, etc.)

Use the wrong knife. (For example: D4 knife is processed with D10 knife)

The program went wrong. (Such as: A7.NC has gone to A9.NC)

The handwheel was turned in the wrong direction during manual operation.

Press the wrong direction during manual rapid feed. (For example: -X press +X)

 

improve:

For depth Z axis tool setting, you must pay attention to the position of the tool. (Bottom surface, top surface, analysis surface, etc.)

Check repeatedly after the count and operation are completed.

When clamping the tool, check it repeatedly with the program sheet and the program before loading it.

The program should go one by one in order.

When using manual operation, the operator himself must strengthen the operation proficiency of the machine tool.

In manual rapid traverse, you can first raise the Z axis to the workpiece before moving.

 

Six, surface accuracy

 

the reason:

Unreasonable cutting parameters, rough surface of the workpiece.

The cutting edge of the tool is not sharp.

The tool clamp is too long, and the blade is too long to avoid the air.

Chip removal, air blowing, oil flushing is not good.

Program the way of knife movement. (You can consider down milling as much as possible)

The workpiece has burrs.

improve:

Cutting parameters, tolerances, margins, and speed feed settings should be reasonable.

The tool requires the operator to inspect and replace it irregularly.

When clamping the tool, the operator is required to clamp as short as possible, and the cutting edge should not be too long.

For flat knife, R knife, and round nose knife, the speed and feed setting should be reasonable.

The workpiece has burrs: it is directly related to our machine tools, cutting tools and cutting methods. So we have to understand the performance of the machine tool and make up the edges with burrs.

 

Seven, chipping

 

Reasons and improvements:

Feed too fast

    —Slow down to a suitable feed rate

Feed too fast at the beginning of cutting

    -Slow down the feed rate at the beginning of cutting

Clamping loose (tool)

    -Clamping

Loose clamping (workpiece)

     -Clamping

Insufficient rigidity (tool)

    —Use the shortest tool allowed, clamp the shank deeper, and try down milling

The cutting edge of the tool is too sharp

    —Change the fragile cutting edge angle, once the edge

Insufficient rigidity of machine tool and tool holder

    —Use a rigid machine tool and tool holder

 

8. Wear

 

Reasons and improvements:

Machine speed is too fast

    —Slow down and add enough coolant

Hardened material

    —Using advanced knives and tool materials, adding surface treatment methods

Chip adhesion

    —Change the feed rate, chip size or use cooling oil or air gun to clean the chips

Improper feed rate (too low)

    —Increase the feed rate, try down milling

Inappropriate cutting angle

    -Change to proper cutting angle

The one-time clearance angle of the tool is too small

    -Change to a larger relief angle

 

Nine, destruction

 

Reasons and improvements:

Feed too fast

    -Slow down the feed rate

Too much cutting

    —Use a smaller cutting amount per edge

The blade length and overall length are too large

    -Clamp the shank deeper, use a short tool, try down milling

Too much wear

    —Re-grind at the beginning

 

Ten, chatter marks

 

Reasons and improvements:

Feed and cutting speed are too fast

    -Correct the feed and cutting speed

Insufficient rigidity (machine tool and tool holder)

    -Use better machine tools and tool holders or change cutting conditions

The back angle is too large

    -Change to a smaller relief angle, and process the cutting edge (use oilstone to sharpen the edge once)

Loose clamping

    —Clamp the workpiece

 

◆ Consider speed and feed

 

The interrelationship of the three factors of speed, feed and depth of cut is the most important factor in determining the cutting effect. Improper feed and speed often result in reduced production, poor workpiece quality, and large tool damage.

 

Use low speed range for:

High hardness materials

Wayward material

Materials that are difficult to cut

Heavy cutting

Minimal tool wear

Longest tool life

 

Use high speed range for

Soft material

Better surface quality

Smaller tool outer diameter

Light cutting

Brittle parts

Manual operation

Maximum processing efficiency

Non-metallic materials

 

Use high feed for

Heavy and rough cutting

Steel structure

Easy to process materials

Roughing tool

Plane cutting

Low tensile strength material

Coarse cutter

 

Use low feed for

Light machining, fine cutting

Brittle structure

Difficult to process materials

Small tool

Deep vertical groove processing

High tensile strength material

Finishing tool