Extruded parts are weak

[gidim]

Hi.

I have everything set and leveled.
When I print the parts, the extruded filament is not bonding correctly to the other printed layers.
I have the same problem with PLA and ABS.
With ABS I have printed the parts at 220C and im using Geeetech Black ABS that i have purchased. Bed temperature is 85C.
For examples, when I print calibration cube with a thin wall, you can stick your fingernail between some of the vertical line. The ABS did not fuse to the previous layers. When I printed something longer, the part simply twisted when I put some twisting pressure.

Any idea what can cause this? Not enough material? temperature is not enough ? How can I test what is the optimum fuse temperature for ABS or PLA? I saw some instruction on the web, but they are talking on how it looks and not how it bonds.

Thanks.

[Sherry]

hi,the optimum fuse temperature for ABS is 240°-250°，PLA is 180°-220°.