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Metal is an important industrial raw material used by any prototype manufacturing company. But because of its properties such as hardness and thermal expansion coefficient, it may easily deform when being processed into thin-walled and thin-plate parts. Along with enhancing tool performance and removing the inner stress of the material beforehand, there are numerous measures that may be taken to decrease the deformation in the rapid prototyping with metal.
1. Symmetrical machining
For those metal prototypes with a massive processing allowance, it's essential to prevent an excessive concentration of heat so as to produce better heat dissipation and reduce thermal deformation. The method used by prototype manufacturing company which may be taken to accomplish this is known as symmetrical machining.
For example, suppose you need to mill a 90 mm thick metal plate to 60 mm thick. If the milling face is immediately turned over to the other side, since each surface has been machined to the final size, the continuous machining allowance will be large, which will cause heat concentration problems, and the flatness of the alloy plate can only reach 5 mm.
However, in the event the symmetrical machining method of 2 sides is used repeatedly, each surface can be machined at least twice until the final size is reached, which is very advantageous for heat dissipation, and the flatness will be controlled to 0.3 mm.
2. Stratified multiple machining
When there is a plurality of cavities to deal with in the rapid prototyping with metal, the cavity wall will be easily twisted due to the uneven force. The best way to solve this problem is to use a layered multiprocessing approach that treats all cavities simultaneously.
The prototype manufacturing company usually divides the component into layers at a time and then machines the layers to the desired size, rather than completing the part at once. The force applied to the component will be more uniform and the likelihood of deformation will be less.
3. Pick a suitable cutting parameter
Cutting force and consequent cutting heat can be reduced by choosing appropriate cutting parameters. In the practice of mechanical processing, even if the cutting edge parameters are larger than normal will contributes to excess cutting power, which may easily make the deformation of these components, in addition to influencing the rigidity of the spindle as well as the durability of this tool.
Among all of the variables of cutting parameters, the largest influence on cutting power is the quantity of spine cutting thickness. However, while reducing the amount of cutting edge tools is helpful to make sure the possibility of deformation in the rapid prototyping with metal is smaller, it may also reduce machining efficiency.
4. Maximize ability of cutting tools
The geometric and material parameters of cutting edge tools have a significant impact on cutting pressure as well as cutting heat. For any prototype manufacturing company, the right determination of cutting edge parameters and tools is thus very essential for reducing the machining distortion in rapid prototyping with metal.
Geometric parameters of the tool that will affect performance:
The front angle has to be suitably configured to maintain blade power, or so the sharp border will get worn out. Correctly setting the front angle may also reduce cutting deformation, make sure smooth chip elimination and decrease cutting pressure and temperature. Do not use the negative front angle tool.
The dimensions of the back angle have an immediate impact on both the flank wear and processed prototype surface quality, and cutting depth is also an important parameter to consider when configuring the back angle. In tough milling, the huge feed speed, heavy cutting load, and big heat imply that the instrument has to consider for heat dissipation. The back angle must, therefore, be smaller. In precision grinding, nevertheless, sharp borders have to decrease the friction between the flank and the machined surface and cut back elastic deformation. In such scenarios, the prototype manufacturing company should choose bigger back corner.
In order to stabilize the milling and reduce the milling force, the helix angle needs to be as big as possible.
Main deflection angle
Properly reducing the principal deflection angle may enhance heat dissipation and decrease the normal temperature of the processing space.
Improve the physical state of cutting tools
Lowering the number of grinding cutter teeth may boost capacity, which is helpful in rapid prototyping of metal alloy. Due to the metal properties, cutting deformation is bigger, and a massive capacity for chip space is necessary. The radius at the bottom of the tank should be large and the number of milling cutter teeth should be reduced.
Precision grinding cutter teeth
Before using the newest knives, utilize good oil stones to grind the front and back edges of your teeth to get rid of burrs and minor zigzag patterns. This manner, not just can cutting warmth be decreased, cutting deformation may also be lessened.
Strictly control tool wear
When the tool wears in the rapid prototyping with metal, the surface roughness of the workpiece will increase, the cutting temperature will increase, and the workpiece deformation will be severe. Therefore, in addition to selecting tool materials with good wear resistance, the wear standard of the tool should not exceed 0.2 mm, otherwise nodules will occur.
5. Various methods
Roughing and finishing require different methods. Roughing requires cutting the excess material on the surface of the blank at the fastest cutting speed in the shortest possible time to form the geometric profile required for finishing. The focus here is on processing efficiency and material removal rates.
On the other hand, finishing in the rapid prototyping with metal requires higher machining accuracy and surface quality. The focus should be on the quality of the milling. When the cutting thickness of the cutting teeth is reduced from the maximum value to zero, the work hardening phenomenon is greatly reduced, and the deformation of the parts can be suppressed to some extent.
6. Two-times compression of thin-walled components
When machining thin-walled metal parts, clamping pressure can lead to deformation. To be able to lower the deformation of the workpiece brought on by clamping, the pressed components ought to be unclamped before completing the last measurement, releasing pressure and restoring components for their original shape prior to reapplying pressure another time.
7. Drilling and milling
Rapid prototyping of metal parts that have cavities presents its own issues. If the milling cutter is directly applied to components, cuttings won't be smooth as a result of the inadequate debris section of the milling cutter. This also contributes to the accumulation of a great deal of cutting back heat, the growth and deformation of components and even possible breakage of this knife or part.
The best way to solve this problem is to drill first and then mill. This involves first drilling with a tool no smaller than the milling cutter and then placing the milling cutter into the hole to start milling.
If you still have a bunch of questions about metal rapid prototyping, go one and read our blog >>> Rapid Prototyping with Metal | Questions and Answers Collected by Best Prototype Companies