{"id":10729,"date":"2026-10-14T07:25:32","date_gmt":"2026-10-14T07:25:32","guid":{"rendered":"https:\/\/ychltools.com\/resources\/cnmg-vs-snmg-inserts\/"},"modified":"2026-10-21T15:01:55","modified_gmt":"2026-10-21T15:01:55","slug":"cnmg-vs-snmg-inserts","status":"publish","type":"page","link":"https:\/\/ychltools.com\/zh\/resources\/cnmg-vs-snmg-inserts\/","title":{"rendered":"CNMG vs SNMG \u5200\u7247: Which Should You Use?"},"content":{"rendered":"

CNMG and SNMG are the two most widely stocked negative turning \u5200\u7247, and they are often interchangeable on the same part. The difference is entirely in the tip angle: CNMG is an 80\u00b0 rhombus, SNMG is a 90\u00b0 square. That one difference drives everything else.<\/p>\n

Side-by-side<\/h2>\n
\n\n\n\n\n\n\n\n\n\n\n\n\n\n
<\/th>\nCNMG<\/th>\nSNMG<\/th>\n<\/tr>\n<\/thead>\n
Shape<\/td>\nRhombic<\/td>\nSquare<\/td>\n<\/tr>\n
Included (tip) angle<\/td>\n80\u00b0<\/strong><\/td>\n90\u00b0<\/strong><\/td>\n<\/tr>\n
Usable cutting edges<\/td>\n4<\/strong><\/td>\n8<\/strong><\/td>\n<\/tr>\n
Edge strength<\/td>\n\u8df3\u8f6cod<\/td>\nBest<\/strong><\/td>\n<\/tr>\n
Reach into corners \/ profiling<\/td>\nBetter<\/strong><\/td>\nLimited<\/td>\n<\/tr>\n
Can produce a square shoulder<\/td>\nApprox. 80\u00b0 \u2014 needs a second operation<\/td>\nYes, true 90\u00b0<\/strong><\/td>\n<\/tr>\n
Cutting force<\/td>\nLower<\/td>\nHigher<\/strong><\/td>\n<\/tr>\n
Cost per edge<\/td>\nHigher<\/td>\nLower<\/strong><\/td>\n<\/tr>\n
Most common size<\/td>\n120408 (12.7 mm IC, 4.76 mm, R0.8)<\/td>\n120408 (same dimensions)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

Why SNMG is stronger<\/h2>\n

A 90\u00b0 corner puts far more material behind the cutting point than an 80\u00b0 corner, and it conducts heat away from the tip better. For the same reason, SNMG handles interrupted cuts, scale and hard skins better. It also has eight edges instead of four, so the cost per edge is roughly half.<\/p>\n

Why CNMG is more popular<\/h2>\n

The 80\u00b0 tip reaches further. It can turn along a shoulder, follow a contour, and get into places a square insert physically cannot. It generates lower radial force, so it is better on slender parts and weaker machines. For general-purpose turning where you do not need a true 90\u00b0 shoulder, CNMG is the more useful tool \u2014 which is why it is the most stocked turning insert in the world.<\/p>\n

The decision rule<\/h2>\n

Work through these in order:<\/p>\n

    \n
  1. Do you need a true 90\u00b0 shoulder or a square step?<\/strong> Yes \u2192 SNMG. No \u2192 continue.<\/li>\n
  2. Is the part slender, thin-walled, or the machine small?<\/strong> Yes \u2192 CNMG (lower radial force).<\/li>\n
  3. Is the cut interrupted, scaly, or heavy?<\/strong> Yes \u2192 SNMG.<\/li>\n
  4. Is cost per edge the main driver, on simple cylindrical work?<\/strong> Yes \u2192 SNMG.<\/li>\n
  5. Anything else \u2014 general profiling, mixed work?<\/strong> \u2192 CNMG.<\/li>\n<\/ol>\n

    A common middle ground<\/h2>\n

    If you want more edges than CNMG but more reach than SNMG, consider WNMG<\/strong> (80\u00b0 trigon, 6 edges) or DNMG<\/strong> (55\u00b0 rhombic, 4 edges, much better reach). And if you need the strongest possible edge for roughing castings, RNMG<\/strong> round \u5200\u7247 outlast both, at the cost of a large radius left on the part.<\/p>\n

    Can you swap them in the same holder?<\/h2>\n

    No.<\/strong> The shape letter in the holder designation must match the insert. A CNMG goes in a holder coded C (for example PCLNR 2020 K12); an SNMG needs an S-coded holder (for example PSBNR 2020 K12). The size digit also has to match \u2014 a 12-size insert needs a K12 holder. If you are unsure, send us the holder code and we will confirm the match.<\/p>\n

    Alternatives worth checking<\/h2>\n