Design for Manufacturability (DFM) plays a crucial role in ensuring that products are not only manufacturable but also meet quality standards. In the injection molding industry, identifying and resolving potential design issues during the DFM stage helps to avoid costly rework, improve efficiency, and ensure product functionality.
This article highlights
90 critical DFM issues that commonly arise during product design and manufacturing, presented in a bilingual format (Chinese-English). Each issue is accompanied by solutions to guide designers and engineers in optimizing their designs for successful production.
1、和滑块干涉的倒钩请加胶填平至滑块可以平顺滑动。
The undercut area where interfere with slide block need to be filled material to help the slide can move smoothly.
2、加胶太多。
The thickening added too thick.
3、加胶面积太大。
The thickening area is too wide.
4、浇口位置移位。
Gate position is moved.
5、滑块拆的位置。
The split line of slide block or the area of slide.
6、此处有尖角，填充困难。
This area is hard to be filled due to the sharp feature.
7、此处钢材太薄，强度不足而且不容易冷却。
The strength of this area is too weak and isn’t easy to get cold due to the steel too thin.
8、圆柱特征要有一半圆不可以折在滑块上，以免粘滑块造成拉白，拉断。
The semicircle of cylinder avoids designing on slide block lest it will be pulled apart or cause drag mark.
9、此处做斜销在作动时会破坏到成品。
The part will be damaged if we make lifter in this area.
10、这个面是装配面，不能加胶。
This is critical surface where is not allow to add material.
11、此处料位太厚，会有缩水，建议减小塑料厚度以改善。
This thick wall area might because sink mark, Please reduce some wall thickness to improve it.
12、此处做滑块的话会有结合线，请确认是否可以接受。
Please confirm whether it is acceptable to has Slide split line if we have slide in this area.
13、请确认此面是不是外观面？
Please confirm whether it is critical surface or not?
14、此处有倒钩，能否减料，使公母模靠破，不做滑块和斜销。
Please confirm whether we can reduce material to the area where have undercut as indicated to have shut off on core and cavity side. No slide block and lifter to be made.
15、请尽快确认这些问题点，否则会影响交期。
Please confirm these questions asap. Otherwise the lead-time will be extended.
16、Gate做在此处的话，盖子打开后看不到Gate的修剪部位。
The trim mark of the gate is not visual after open the top case if the gate position is designed like it.
17、加大拔模角，以便脱模顺利。
We would suggest to enlarging draft to help tool released.
18、如果GATE一定要做在你们指定的位置的话，那还不如做在这一侧，这样的话还可以减少这个位置的缩水。
If you insist that the gate position have to be as original design then we would further recommend to have it to the area where indicate as it can avoid shrink problem in this area.
19、P.L面开在此处，模具上会有尖角和刀口，对模具寿命有影响。
There are sharp edges if set the parting line at here, It will reduce the tool life.
20、请问此产品的面是否为外观面？表面做什么处理？是触纹/抛光？
Can you tell me whether the surface of this part is a visible/esthetic one? What will we do for its surface? Texture or Polishing?
21、请问产品这个面是否加顶针或顶块？产品允许加扁顶针吗？
Does this part need an ejector pin or an ejector bar? Can we add an ejector blade?
22、这个产品的柱位元我们打算做司筒（或镶针）可以吗？
Can we add ejector sleeves or ejector pins in the boss of this part?
23、这个位置有倒勾不能脱模，我们打算做滑块，在此面上会有分模线，你接受吗？
There's an undercut at this position and it needs a slider. It will also have a parting line on this side, is that OK?
24、我们打算在这个位置做斜顶或内滑块，有问题吗？
We will make the lifter or inner slider in this position, will that be a problem?
25、你提供的2D产品图跟3D产品图不一致，请问哪一图正确？
The 2D and 3D drawing you provided is not the same, can you tell me which one is correct?
26、你提供的3D产品图里有的地方没有脱模角，有的地方胶位太厚，有的地方胶位元太薄，这些产品问题我们可以自己修改吗？修改后会给图给您确认。
There is no draft angle in the 3D drawing, some materials are too thick, and some place are too thin. Can we modify this part by ourselves? We will send the drawing to you for you to check after we modify it.
27、按你们提供的缩水率千分之五，这个模具的尺寸已做到模具图面要求。
According to the shrinkage one over two hundred, the mold has been done in the right dimension.
28、注塑出来的产品不符合你们的产品图，请确认你们材料的缩水率是否正确？
The part falls short to your part drawing. Are you sure the shrinkage is right?
29、产品的这个位置太小，导致模具钢料太薄，能加宽此位置吗？
This position is too small and will make the steel material here too thin, can we widen it here?
30、斜顶与后面的Boss空间太小，斜顶在运动时会涉到柱子，能移动这个柱子的位置吗？
The angular lifter interferes with the boss during ejection. Please consider changing the position of the boss.
31、这个筋骨位胶厚太薄，而且高度偏高；注塑时很难填充这个筋骨，可以增加这个筋骨位的厚度吗？
The rib here is too thin and on the high side, so it will be difficult to fill here when we do the injection, can you increase the thickness of this rib?
32、你是想将此筋骨位的高度加高/减低吗？假如加胶，我们将用放电方式加深。
Will you increase/decrease the material on this rib? If add the material, we will modify it with EDM process.
33、减胶修改有两种做法：
- 做镶件；
- 烧焊；因为镶件的底部有运水，我们简单的做法是烧焊处理。你可以接受吗？
There are two options if decrease the material:
- 1.Make inserts;
- 2.Welding, because there is water in the bottom of the insert, is that OK?
34、这个样板的筋骨位底部烧焦，是因为排气不良；我们可以在筋骨位的中间增加一个镶件。
This sample has been burned in the bottom because the venting is not good, we can add an insert in the middle of the rib.
35、重做镶件大约需要5-6天时间。
It will take about 5 or 6 days to redo the insert.
36、产品的这个面我们已经做了晒纹处理；如果需要加胶，这个面我们需要重新外发晒纹。可能需要几天时间。所以我们直接以铜公放电的火花纹取代你要求的纹路，你可以接受吗？
We have made the texture on this side, if we add material, it will take some days to remake the texture by out-resourcing, so we suggest using the texture by EDM instead, is that OK?
37、模具是用公制/英制的配件？
Is this mold dimension measured in inches or meters?
38、需要备用件吗？
Does it need spare parts?
39、模具上铭牌上的刻字内容是由你们提供的吗？你们什么时候可以送这些刻字资料？
Will you provide the engraving content of the plate of this mold to us? When will you send it?
40、可否提供此模具生产时注塑机的型号和相关资料？如：啤机大小、呵林柱尺寸、顶棍孔尺寸等。
Can you provide the type of injection machine and other related information of this mold to us? Such as the boss dimension, the hole's dimension of the ejector pin and the size of the injection machine and so on.
41、这个问题我需要与其他同事商议会再答复你。
I need to discuss this problem with the other colleagues and then I will reply back to you.
42、我们将尽力达成你的计划，如有异常，会及时通知你。
We will try our best to complete your plan, if there are any complications, we will notify you immediately.
43、这个产品的长度为330.12MM，宽度为78.96MM，高度为45MM，胶厚为2MM，重量为70.63g。
The length of this part is 330.12MM, Width is 78.96MM, height is 45MM, thickness is 2MM, weight is 70.63g.
44、试模注塑机型号为250T，胶料颜色为黑色，产品外表面晒纹处理，内表面为抛光。
The injection machine is 250T, the material is black, the outside of the part has texture, inner side needs polishing.
45、和滑块干涉的倒勾需加胶填平至滑块可以顺利滑动。
The undercut area interferes with the slide block and needs to be filled with material to help the slider move smoothly.
46、此面是否为特殊要求，能否有顶针痕。
Please confirm whether it is a critical surface or not and if we can have E.J. pin marks on it.
47、此处Gate做潜伏式灌顶针的话，背后的外观面有冲料痕，而成品又是黑色的，会很明显。
If the design of the gate has to be a sub. Gate, then the back surface of the part will have serious flow marks due to the black color.
48、P.L开在此处不合理，模具加工困难；P.L应该改为图示的一样。
This area is not suitable to have a Parting line because the tool will become more complicated; therefore, we recommend to have the Parting line as indicated.
49、产品粘母模的几率很大，能否在公模加倒勾/拉料顶针或者公模保留E.D.M纹，开模时使成品留在公模一侧。
There is possible sticking on cavity; therefore, please confirm whether it can make undercuts, snatch pins or leave coarse E.D.M. on the core to snatch the part on.
50、此处料厚段差很大，成品表面会有应力痕，是否接受？
Please confirm whether it is acceptable to have stress lines on the surface because the thickness is not equal.
51、请注明何处为外观面，能否提供2D图和注意事项。
Please advise where the critical surface is. Please also provide us a 2D drawing with critical dimensions.
52、红色所示处是有问题的地方，请特别注意。
Please note the red highlights because those areas have problems.
53、成品设计此处有问题，建议如下图所示修改。
We would suggest using the attached part design as the current design has problems.
54、此处改为一圆球形的凹槽。
We suggest modifying it as a globe recess.
55、此处大滑块上走小滑块，小滑块要先退，大滑块要做延迟。
The inside small slide block will recede first and the parent slide block have to postpone sliding.
56、滑块要用液压油缸抽芯以保证开合模顺序。
The slide pins will use an oil cylinder to assure that the process is in proper order.
57、这个面有装配，加料的话装配时会顶住，如图所示。
We cannot add material to this surface because it will intervene between the two parts when it is assembled.
Please see the sketch attached.
58、可降低斜销面，增加成品些许肉厚来做变化。
To descend the surface of lifter in order to thicken the part.
59、一半做斜销，一半做自然。
One half side will have the lifter and the other half will be solid/nature.
60、此处两个柱子重叠，有倒勾，不能做自然，要做SLIDE。
These two bosses are overlapping with undercut therefore it cannot be made as solid. We suggest making it with a slide block.
61、此处强迫顶出。
This area needs force ejection.
62、公模两段开模，这个地方先退。
Here will be a double ejection for forward and receding.
63、此处做镶件会有夹线，能否接受。
Please confirm whether it is acceptable that there will be a split line here.
64、此面公母模1度靠破，会有段差，是否接受。
Please confirm whether it is ok to have mismatch to the area where there is 1 degree of shut off in Core / Cavity side.
65、这个尺寸是否可加大。
Please confirm whether we can enlarge this dimension.
66、此处加一个凹槽，胶片的弹出效果会更好一些，试模后看装配的效果再做修正。
It will affect the elastic of the film better if we add a recess. See how it will affect the assembly parts, and then make your decision.
67、此处有倒勾，建议将剖面线所示部位CUT即可避免此处的倒勾。
There is an undercut here, we suggest cutting out the indicated part as it highlighted to avoid an undercut.
68、成型后SUB GATE要修平。
The gate (sub gate) needs to be trimmed evenly after being moulded.
69、此处倒勾先垂直顶出，之后再手动取出。
This area of the undercut needs to be ejected vertically, then taken out manually.
70、这两个面都有滑块，GATE改在此处改不到。
The gate is not suitable in this area because there are two sliding blocks sealing off this area.
71、此处加做一个旋转GATE，射出时方便调整成品的品质。
We would suggest placing a runner shut-off insert to adjust the volume of part filling.
72、此倒勾在滑块上强迫脱模，倒勾是否可以减少到0.6。
This undercut will be force ejected out, Please confirm whether it can be reduced to 0.6 mm.
73、此柱子无法脱模，请确认是否是在转图时错误，能否提供客户的原始图档data。
This boss is not releasable. Please check the file again and if possible, please re-send us the original draft.
74、此柱子是实心的，会缩水。
This boss will shrink because it is a solid boss.
75、这个面是否要咬花，咬花编号是什么，最小的拔模角要多大。
Please confirm whether this surface needs to be textured or not. Please advise texture specs. Also, what's the min. draft.
76、这个面是否要打光，贴标签。
Please confirm whether this surface needs to be polished and stuck on a sticker.
77、红色显示的几个面拔模角太小，出模时会拉伤，建议加大拔模角。
The red highlighted area has a problem of a small draft angle. We suggest enlarging the draft to avoid causing drag marks on the part.
78、此RIB太薄，会填充不足。
This rib can not be filled properly because it is too thin.
79、此RIB太厚，会缩水。
This rib will have a shrink problem because it is too thick.
80、此处倒勾出模困难，建议先不做倒勾，成型后再二次加工，但要做治具，费用要另外计算。
There are problems with this current design, we recommend doing this undercut as an alternative but there will be additional costs.
81、柱子底部都要做火山口。
The base of all bosses require a crater to avoid shrinkage.
82、镶件、P.L.面有充足排气坑，P.L.面要开环形排气槽，并能将气体排到模外
Insert/PL should have adequate venting, PL should have around slot for venting.
83、顶棍孔镶件端面距离底板面0.5mm，攻M20牙。
The surface of KO insert should below bottom plate 0.5mm, thread M20.
84、排气槽距封胶位10-15mm。
Venting slot distance from the seal off position 10-15mm.
85、底面板均要有隔热板，DME规格1/4厚。
Top/Bottom plate must have insulator plate, DME standard 1/4'H.
86、此处有进胶及方顶，所以无法在此处加水路。
This area has runner & square ejects then can not set up a cooling system.
87、进胶点改成在方顶里做潜水的形式，方顶具体位置需要模流分析后确定。此种进胶方式削除较困难，会有残余（表面不平或高或低），而且产品表面压力大后很容易有阴影。
Change to one sub-gate/square gate (1.2x4mm). After the mold flow analysis, xxx will advise where to set the gate location. This gate may hard to remove the runner. It also may have shadow on the surface. Above will seriously affect the texture & cosmetics.
88、依照客户产品原有拔模角度产品会沾母模，所以我们建议此处分模线需要改在上面。
To prevent from part stick on the cavity side, MGF advises the PL change to this location.
89、为防止滑块粘母模，产品此处R不能出在滑块上（请参考我们的初步3D拆模）。
To prevent from scrape, the slide can not cover the radius (xxx has 3D file for reference).
90、能否往箭头方向移动1mm？
Can this stage move 1 mm as the Pink arrow direction?
Conclusion
Identifying and resolving these common DFM issues is essential for achieving a successful injection molding process. Proactively addressing challenges like gate positioning, slide block design, and material thickness ensures smoother production, higher product quality, and cost efficiency.
At JBR, we specialize in delivering optimized DFM solutions for injection molding projects. Our expertise in identifying and addressing design challenges enables us to provide superior results for our clients. Contact us today to learn how we can help enhance your product designs and manufacturing processes.
